UI hangs When booting Live version of Ubuntu 18.04

My system:
Graphics: Card: Advanced Micro Devices [AMD/ATI] Device 98e4
           bus-ID: 00:01.0 chip-ID: 1002:98e4
           Display Server: X.Org 1.18.4 drivers: ati,amdgpu (unloaded: fbdev,vesa,radeon)
           Resolution: 1366x768@60.03hz
           GLX Renderer: Gallium 0.4 on AMD STONEY (DRM 3.1.0, LLVM 3.8.0)
           GLX Version: 3.0 Mesa 11.2.0 Direct Rendering: Yes

    description: Notebook
    product: Inspiron 15-3565 (078E)
    vendor: Dell Inc.
    version: 1.7.0
    serial: 9LWJ6L2
    width: 64 bits
    capabilities: smbios-3.0 dmi-3.0 smp vsyscall32
    configuration: boot=normal chassis=notebook family=Inspiron sku=078E uuid=44454C4C-4C00-1057-804A-B9C04F364C32
  *-core
       description: Motherboard
       product: Inspiron 15-3565
       vendor: Dell Inc.
       physical id: 0
       version: A00
       serial: .9LWJ6L2.CNWSC0083900Q7.
       slot: Default string
     *-firmware
          description: BIOS
          vendor: Dell Inc.
          physical id: 0
          version: 1.7.0
          date: 10/23/2017
          size: 64KiB
          capacity: 8128KiB
          capabilities: pci pnp upgrade shadowing cdboot bootselect edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int14serial int17printer acpi usb biosbootspecification netboot uefi
     *-cache:0
          description: L1 cache
          physical id: 17
          slot: L1 CACHE
          size: 160KiB
          capacity: 160KiB
          clock: 1GHz (1.0ns)
          capabilities: pipeline-burst internal write-back unified
          configuration: level=1
     *-cache:1
          description: L2 cache
          physical id: 18
          slot: L2 CACHE
          size: 1MiB
          capacity: 1MiB
          clock: 1GHz (1.0ns)
          capabilities: pipeline-burst internal write-back unified
          configuration: level=2
     *-memory
          description: System Memory
          physical id: 25
          slot: System board or motherboard
          size: 4GiB
        *-bank:0
             description: SODIMM DDR4 [empty]
             product: A1_PartNum0
             vendor: 000000000000
             physical id: 0
             serial: A1_SerialNum0
             slot: DIMM 0
             width: 64 bits
        *-bank:1
             description: SODIMM DDR4 Synchronous Unbuffered (Unregistered) 2400 MHz (0.4 ns)
             product: 4ATF51264HZ-2G3E1
             vendor: 009C360B0000
             physical id: 1
             serial: 1B0B3BB5
             slot: DIMM 1
             size: 4GiB
             width: 64 bits
             clock: 2400MHz (0.4ns)
     *-cpu
          description: CPU
          product: AMD A6-9200 RADEON R4, 5 COMPUTE CORES 2C+3G
          vendor: Advanced Micro Devices [AMD]
          physical id: 2c
          bus info: cpu@0
          version: AMD A6-9200 RADEON R4, 5 COMPUTE CORES 2C+3G
          slot: P0
          size: 1620MHz
          capacity: 2GHz
          width: 64 bits
          clock: 100MHz
          capabilities: x86-64 fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp constant_tsc rep_good acc_power nopl nonstop_tsc cpuid extd_apicid aperfmperf pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs xop skinit wdt lwp fma4 tce nodeid_msr tbm perfctr_core perfctr_nb bpext ptsc mwaitx cpb hw_pstate vmmcall fsgsbase bmi1 avx2 smep bmi2 xsaveopt arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_vmsave_vmload vgif overflow_recov cpufreq
          configuration: cores=2 enabledcores=2 threads=2
     *-pci:0
          description: Host bridge
          product: Advanced Micro Devices, Inc. [AMD]
          vendor: Advanced Micro Devices, Inc. [AMD]
          physical id: 100
          bus info: pci@0000:00:00.0
          version: 00
          width: 32 bits
          clock: 33MHz
        *-generic:0 UNCLAIMED
             description: IOMMU
             product: Advanced Micro Devices, Inc. [AMD]
             vendor: Advanced Micro Devices, Inc. [AMD]
             physical id: 0.2
             bus info: pci@0000:00:00.2
             version: 00
             width: 32 bits
             clock: 33MHz
             capabilities: msi ht bus_master cap_list
             configuration: latency=0
        *-display UNCLAIMED
             description: VGA compatible controller
             product: Advanced Micro Devices, Inc. [AMD/ATI]
             vendor: Advanced Micro Devices, Inc. [AMD/ATI]
             physical id: 1
             bus info: pci@0000:00:01.0
             version: c0
             width: 64 bits
             clock: 33MHz
             capabilities: pm pciexpress msi vga_controller bus_master cap_list
             configuration: latency=0
             resources: memory:e8000000-efffffff memory:f0000000-f07fffff ioport:f000(size=256) memory:feb00000-feb3ffff memory:c0000-dffff
        *-multimedia:0
             description: Audio device
             product: Advanced Micro Devices, Inc. [AMD/ATI]
             vendor: Advanced Micro Devices, Inc. [AMD/ATI]
             physical id: 1.1
             bus info: pci@0000:00:01.1
             version: 00
             width: 64 bits
             clock: 33MHz
             capabilities: pm pciexpress msi bus_master cap_list
             configuration: driver=snd_hda_intel latency=0
             resources: irq:64 memory:feb64000-feb67fff
        *-pci:0
             description: PCI bridge
             product: Advanced Micro Devices, Inc. [AMD]
             vendor: Advanced Micro Devices, Inc. [AMD]
             physical id: 2.4
             bus info: pci@0000:00:02.4
             version: 00
             width: 32 bits
             clock: 33MHz
             capabilities: pci pm pciexpress msi ht normal_decode bus_master cap_list
             configuration: driver=pcieport
             resources: irq:57 ioport:e000(size=4096) memory:fea00000-feafffff ioport:f0800000(size=1048576)
           *-network
                description: Ethernet interface
                product: RTL8101/2/6E PCI Express Fast/Gigabit Ethernet controller
                vendor: Realtek Semiconductor Co., Ltd.
                physical id: 0
                bus info: pci@0000:14:00.0
                logical name: enp20s0
                version: 07
                serial: 58:8a:5a:3e:ba:90
                size: 10Mbit/s
                capacity: 100Mbit/s
                width: 64 bits
                clock: 33MHz
                capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation
                configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=half firmware=rtl8106e-1_0.0.1 06/29/12 latency=0 link=no multicast=yes port=MII speed=10Mbit/s
                resources: irq:63 ioport:e000(size=256) memory:fea00000-fea00fff memory:f0800000-f0803fff
        *-pci:1
             description: PCI bridge
             product: Advanced Micro Devices, Inc. [AMD]
             vendor: Advanced Micro Devices, Inc. [AMD]
             physical id: 2.5
             bus info: pci@0000:00:02.5
             version: 00
             width: 32 bits
             clock: 33MHz
             capabilities: pci pm pciexpress msi ht normal_decode bus_master cap_list
             configuration: driver=pcieport
             resources: irq:58 memory:fe600000-fe7fffff
           *-network
                description: Wireless interface
                product: QCA9377 802.11ac Wireless Network Adapter
                vendor: Qualcomm Atheros
                physical id: 0
                bus info: pci@0000:16:00.0
                logical name: wlp22s0
                version: 31
                serial: 9c:30:5b:e4:fa:41
                width: 64 bits
                clock: 33MHz
                capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
                configuration: broadcast=yes driver=ath10k_pci driverversion=4.15.0-20-generic firmware=WLAN.TF.1.0-00002-QCATFSWPZ-5 ip=192.168.1.144 latency=0 link=yes multicast=yes wireless=IEEE 802.11
                resources: irq:65 memory:fe600000-fe7fffff
        *-generic:1 UNCLAIMED
             description: Encryption controller
             product: Advanced Micro Devices, Inc. [AMD]
             vendor: Advanced Micro Devices, Inc. [AMD]
             physical id: 8
             bus info: pci@0000:00:08.0
             version: 00
             width: 64 bits
             clock: 33MHz
             capabilities: msix ht pm bus_master cap_list
             configuration: latency=0
             resources: memory:f0900000-f091ffff memory:fe900000-fe9fffff memory:feb6f000-feb6ffff memory:feb6a000-feb6bfff
        *-multimedia:1
             description: Audio device
             product: Advanced Micro Devices, Inc. [AMD]
             vendor: Advanced Micro Devices, Inc. [AMD]
             physical id: 9.2
             bus info: pci@0000:00:09.2
             version: 00
             width: 32 bits
             clock: 33MHz
             capabilities: pm bus_master cap_list
             configuration: driver=snd_hda_intel latency=0
             resources: irq:11 memory:feb60000-feb63fff
        *-usb:0
             description: USB controller
             product: FCH USB XHCI Controller
             vendor: Advanced Micro Devices, Inc. [AMD]
             physical id: 10
             bus info: pci@0000:00:10.0
             version: 20
             width: 64 bits
             clock: 33MHz
             capabilities: pm msi msix pciexpress xhci bus_master cap_list
             configuration: driver=xhci_hcd latency=0
             resources: irq:11 memory:feb68000-feb69fff
           *-usbhost:0
                product: xHCI Host Controller
                vendor: Linux 4.15.0-20-generic xhci-hcd
                physical id: 0
                bus info: usb@2
                logical name: usb2
                version: 4.15
                capabilities: usb-2.00
                configuration: driver=hub slots=4 speed=480Mbit/s
              *-usb
                   description: Bluetooth wireless interface
                   vendor: Atheros Communications, Inc.
                   physical id: 1
                   bus info: usb@2:1
                   version: 0.01
                   capabilities: bluetooth usb-2.01
                   configuration: driver=btusb maxpower=100mA speed=12Mbit/s
           *-usbhost:1
                product: xHCI Host Controller
                vendor: Linux 4.15.0-20-generic xhci-hcd
                physical id: 1
                bus info: usb@3
                logical name: usb3
                version: 4.15
                capabilities: usb-3.00
                configuration: driver=hub slots=4 speed=5000Mbit/s
        *-storage
             description: SATA controller
             product: FCH SATA Controller [AHCI mode]
             vendor: Advanced Micro Devices, Inc. [AMD]
             physical id: 11
             bus info: pci@0000:00:11.0
             version: 4b
             width: 32 bits
             clock: 66MHz
             capabilities: storage pm ahci_1.0 bus_master cap_list
             configuration: driver=ahci latency=32
             resources: irq:4 ioport:f140(size=8) ioport:f130(size=4) ioport:f120(size=8) ioport:f110(size=4) ioport:f100(size=16) memory:feb6d000-feb6d3ff
        *-usb:1
             description: USB controller
             product: FCH USB EHCI Controller
             vendor: Advanced Micro Devices, Inc. [AMD]
             physical id: 12
             bus info: pci@0000:00:12.0
             version: 49
             width: 32 bits
             clock: 66MHz
             capabilities: pm debug ehci bus_master cap_list
             configuration: driver=ehci-pci latency=32
             resources: irq:11 memory:feb6c000-feb6c0ff
           *-usbhost
                product: EHCI Host Controller
                vendor: Linux 4.15.0-20-generic ehci_hcd
                physical id: 1
                bus info: usb@1
                logical name: usb1
                version: 4.15
                capabilities: usb-2.00
                configuration: driver=hub slots=2 speed=480Mbit/s
              *-usb
                   description: USB hub
                   vendor: Advanced Micro Devices, Inc.
                   physical id: 1
                   bus info: usb@1:1
                   version: 0.18
                   capabilities: usb-2.00
                   configuration: driver=hub maxpower=100mA slots=4 speed=480Mbit/s
                 *-usb:0
                      description: Video
                      product: Integrated_Webcam_HD
                      vendor: CN0F08KGLOG0082BA075A02
                      physical id: 1
                      bus info: usb@1:1.1
                      version: 52.68
                      serial: 200901010001
                      capabilities: usb-2.00
                      configuration: driver=uvcvideo maxpower=500mA speed=480Mbit/s
                 *-usb:1
                      description: Human interface device
                      product: Touchscreen
                      vendor: ELAN
                      physical id: 2
                      bus info: usb@1:1.2
                      version: 57.12
                      capabilities: usb-2.00
                      configuration: driver=usbhid maxpower=100mA speed=12Mbit/s
                 *-usb:2
                      description: Generic USB device
                      product: USB2.0-CRW
                      vendor: Generic
                      physical id: 3
                      bus info: usb@1:1.3
                      version: 39.60
                      serial: 20100201396000000
                      capabilities: usb-2.00
                      configuration: driver=rtsx_usb maxpower=500mA speed=480Mbit/s
                 *-usb:3
                      description: Mass storage device
                      product: USB 2.0 FD
                      vendor: PNY Technologies
                      physical id: 4
                      bus info: usb@1:1.4
                      logical name: scsi2
                      version: 11.00
                      serial: AD48HD08000002871
                      capabilities: usb-2.00 scsi emulated scsi-host
                      configuration: driver=usb-storage maxpower=200mA speed=480Mbit/s
                    *-disk
                         description: SCSI Disk
                         product: USB 2.0 FD
                         vendor: PNY
                         physical id: 0.0.0
                         bus info: scsi@2:0.0.0
                         logical name: /dev/sdb
                         logical name: /cdrom
                         version: 1100
                         serial: AA00000000000485
                         size: 15GiB (16GB)
                         capabilities: removable
                         configuration: ansiversion=4 logicalsectorsize=512 mount.fstype=iso9660 mount.options=ro,noatime,nojoliet,check=s,map=n,blocksize=2048 sectorsize=512 state=mounted
                       *-medium
                            physical id: 0
                            logical name: /dev/sdb
                            logical name: /cdrom
                            size: 15GiB (16GB)
                            capabilities: partitioned partitioned:dos
                            configuration: mount.fstype=iso9660 mount.options=ro,noatime,nojoliet,check=s,map=n,blocksize=2048 signature=1482d141 state=mounted
                          *-volume
                               description: Windows FAT volume
                               vendor: mkfs.fat
                               physical id: 2
                               logical name: /dev/sdb2
                               version: FAT12
                               serial: 044e-ac17
                               size: 15EiB
                               capabilities: primary boot fat initialized
                               configuration: FATs=2 filesystem=fat
        *-serial
             description: SMBus
             product: FCH SMBus Controller
             vendor: Advanced Micro Devices, Inc. [AMD]
             physical id: 14
             bus info: pci@0000:00:14.0
             version: 4b
             width: 32 bits
             clock: 66MHz
             configuration: driver=piix4_smbus latency=0
             resources: irq:0
        *-isa
             description: ISA bridge
             product: FCH LPC Bridge
             vendor: Advanced Micro Devices, Inc. [AMD]
             physical id: 14.3
             bus info: pci@0000:00:14.3
             version: 11
             width: 32 bits
             clock: 66MHz
             capabilities: isa bus_master
             configuration: latency=0
     *-pci:1
          description: Host bridge
          product: Advanced Micro Devices, Inc. [AMD]
          vendor: Advanced Micro Devices, Inc. [AMD]
          physical id: 101
          bus info: pci@0000:00:02.0
          version: 00
          width: 32 bits
          clock: 33MHz
     *-pci:2
          description: Host bridge
          product: Advanced Micro Devices, Inc. [AMD]
          vendor: Advanced Micro Devices, Inc. [AMD]
          physical id: 102
          bus info: pci@0000:00:03.0
          version: 00
          width: 32 bits
          clock: 33MHz
     *-pci:3
          description: Host bridge
          product: Advanced Micro Devices, Inc. [AMD]
          vendor: Advanced Micro Devices, Inc. [AMD]
          physical id: 103
          bus info: pci@0000:00:09.0
          version: 00
          width: 32 bits
          clock: 33MHz
     *-pci:4
          description: Host bridge
          product: Advanced Micro Devices, Inc. [AMD]
          vendor: Advanced Micro Devices, Inc. [AMD]
          physical id: 104
          bus info: pci@0000:00:18.0
          version: 00
          width: 32 bits
          clock: 33MHz
     *-pci:5
          description: Host bridge
          product: Advanced Micro Devices, Inc. [AMD]
          vendor: Advanced Micro Devices, Inc. [AMD]
          physical id: 105
          bus info: pci@0000:00:18.1
          version: 00
          width: 32 bits
          clock: 33MHz
     *-pci:6
          description: Host bridge
          product: Advanced Micro Devices, Inc. [AMD]
          vendor: Advanced Micro Devices, Inc. [AMD]
          physical id: 106
          bus info: pci@0000:00:18.2
          version: 00
          width: 32 bits
          clock: 33MHz
     *-pci:7
          description: Host bridge
          product: Advanced Micro Devices, Inc. [AMD]
          vendor: Advanced Micro Devices, Inc. [AMD]
          physical id: 107
          bus info: pci@0000:00:18.3
          version: 00
          width: 32 bits
          clock: 33MHz
     *-pci:8
          description: Host bridge
          product: Advanced Micro Devices, Inc. [AMD]
          vendor: Advanced Micro Devices, Inc. [AMD]
          physical id: 108
          bus info: pci@0000:00:18.4
          version: 00
          width: 32 bits
          clock: 33MHz
          configuration: driver=fam15h_power
          resources: irq:0
     *-pci:9
          description: Host bridge
          product: Advanced Micro Devices, Inc. [AMD]
          vendor: Advanced Micro Devices, Inc. [AMD]
          physical id: 109
          bus info: pci@0000:00:18.5
          version: 00
          width: 32 bits
          clock: 33MHz
     *-scsi:0
          physical id: 1
          logical name: scsi0
          capabilities: emulated
        *-disk
             description: ATA Disk
             product: TOSHIBA MQ01ABD1
             vendor: Toshiba
             physical id: 0.0.0
             bus info: scsi@0:0.0.0
             logical name: /dev/sda
             version: 3D
             serial: 28HHTBRUT
             size: 931GiB (1TB)
             capabilities: gpt-1.00 partitioned partitioned:gpt
             configuration: ansiversion=5 guid=9b216b98-417f-4309-b3f2-4d2ef82cc374 logicalsectorsize=512 sectorsize=4096
           *-volume:0
                description: Windows FAT volume
                vendor: MSDOS5.0
                physical id: 1
                bus info: scsi@0:0.0.0,1
                logical name: /dev/sda1
                version: FAT32
                serial: 6435-4b7a
                size: 495MiB
                capacity: 499MiB
                capabilities: boot precious readonly hidden nomount fat initialized
                configuration: FATs=2 filesystem=fat label=ESP name=EFI system partition
           *-volume:1
                description: reserved partition
                vendor: Windows
                physical id: 2
                bus info: scsi@0:0.0.0,2
                logical name: /dev/sda2
                serial: bf7e2054-fab1-43e7-80f5-15f088082e2f
                capacity: 127MiB
                capabilities: nofs precious readonly hidden nomount
                configuration: name=Microsoft reserved partition
           *-volume:2
                description: Windows NTFS volume
                vendor: Windows
                physical id: 3
                bus info: scsi@0:0.0.0,3
                logical name: /dev/sda3
                logical name: /media/mint/OS
                version: 3.1
                serial: 3e016f63-f91e-5947-a7ed-8e885e7ce9ca
                size: 916GiB
                capacity: 916GiB
                capabilities: ntfs initialized
                configuration: clustersize=4096 created=2018-03-10 18:08:19 filesystem=ntfs label=OS mount.fstype=fuseblk mount.options=rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096 name=Basic data partition state=mounted
           *-volume:3
                description: Windows NTFS volume
                vendor: Windows
                physical id: 4
                bus info: scsi@0:0.0.0,4
                logical name: /dev/sda4
                version: 3.1
                serial: 0806-480a
                size: 879MiB
                capacity: 906MiB
                capabilities: boot precious readonly hidden nomount ntfs initialized
                configuration: clustersize=4096 created=2018-09-16 05:06:27 filesystem=ntfs modified_by_chkdsk=true mounted_on_nt4=true resize_log_file=true state=dirty upgrade_on_mount=true
           *-volume:4
                description: Windows NTFS volume
                vendor: Windows
                physical id: 5
                bus info: scsi@0:0.0.0,5
                logical name: /dev/sda5
                version: 3.1
                serial: f648-b5d7
                size: 12GiB
                capacity: 12GiB
                capabilities: boot precious readonly hidden nomount ntfs initialized
                configuration: clustersize=4096 created=2018-03-10 21:10:57 filesystem=ntfs label=Image modified_by_chkdsk=true mounted_on_nt4=true resize_log_file=true state=dirty upgrade_on_mount=true
           *-volume:5
                description: Windows NTFS volume
                vendor: Windows
                physical id: 6
                bus info: scsi@0:0.0.0,6
                logical name: /dev/sda6
                version: 3.1
                serial: 5ccd-6bfa
                size: 1082MiB
                capacity: 1091MiB
                capabilities: boot precious readonly hidden nomount ntfs initialized
                configuration: clustersize=4096 created=2018-03-10 20:46:02 filesystem=ntfs label=DELLSUPPORT modified_by_chkdsk=true mounted_on_nt4=true resize_log_file=true state=dirty upgrade_on_mount=true
     *-scsi:1
          physical id: 2
          logical name: scsi1
          capabilities: emulated
        *-cdrom
             description: DVD-RAM writer
             product: DVD+-RW GU90N
             vendor: HL-DT-ST
             physical id: 0.0.0
             bus info: scsi@1:0.0.0
             logical name: /dev/cdrom
             logical name: /dev/cdrw
             logical name: /dev/dvd
             logical name: /dev/dvdrw
             logical name: /dev/sr0
             version: A1C3
             capabilities: removable audio cd-r cd-rw dvd dvd-r dvd-ram
             configuration: ansiversion=5 status=nodisc
  *-battery
       description: Nickel Cadmium Battery
       product: DELL 991XP7B
       vendor: LGC-LGC2.80
       physical id: 1
       serial: 57474
       slot: Location of the battery
       capacity: 41440mWh
       configuration: voltage=14.8V

Step to reproduce:
Note: I discovered this defect when trying to load a Live image of Mint 19.1. I've duplicated it using Ubuntu and Xubuntu. I'm logging it here because Ubuntu is the "base" codebase.

1. I boot from my USB drive. Usually, the UI loads, but sometimes I only get a blank screen.

2. Connect to Wifi.

3. After using the OS for a while, everything freezes. The mouse and keyboard inputs don't work.

4. This happens every time.

What I expected to happen: the UI and everything doesn't freeze. :-)

More info: I reported this problem here: https://www.linuxquestions.org/questions/linux-mint-84/problems-with-xfce-19-1-live-us-4175644671/
There might be some useful info here.

I'll be happy to assist, test or answer questions about this issue.

I suspect that this is related to the Desktop env. When I run Lubuntu, it works well. I've tested LXLE 16.04 (same Ubuntu version) and it works well also.