Fails to load GNOME desktop

What causes this:
1. Type wrong password to login first.
2. Type right password and login.

After that:
There is nothing on screen but for mouse pointer and dark-purple wallpaper.
And no access to HDD/SSD, because access lamp doesn't flash.

How frequently:
Every time I did that.

Supplement:
I can't distinguish which causes this problem, xorg or gnome.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xorg 1:7.7+19ubuntu7
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
BootLog: Error: [Errno 13] 許可がありません: '/var/log/boot.log'
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Mon Apr 30 12:14:51 2018
DistUpgraded: Fresh install
DistroCodename: bionic
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes
GpuHangFrequency: Several times a week
GpuHangReproducibility: Occurs more often under certain circumstances
GpuHangStarted: Immediately after installing this version of Ubuntu
GraphicsCard:
 Intel Corporation 4th Gen Core Processor Integrated Graphics Controller [8086:0416] (rev 06) (prog-if 00 [VGA controller])
   Subsystem: Toshiba America Info Systems 4th Gen Core Processor Integrated Graphics Controller [1179:0007]
InstallationDate: Installed on 2018-04-27 (3 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 002: ID 04f2:b3b2 Chicony Electronics Co., Ltd
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: TOSHIBA dynabook R73/NW56E
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=ja_JP.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-20-generic root=UUID=e1d39ab2-7146-4fd5-985f-7361d7a78a0c ro quiet splash vt.handoff=1
SourcePackage: xorg
Symptom: display
Title: Xorg freeze
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/23/2015
dmi.bios.vendor: TOSHIBA
dmi.bios.version: Version 4.80
dmi.board.asset.tag: 0000000000
dmi.board.name: dynabook R73/NW56E
dmi.board.vendor: TOSHIBA
dmi.board.version: Version A0
dmi.chassis.asset.tag: 0000000000
dmi.chassis.type: 10
dmi.chassis.vendor: TOSHIBA
dmi.chassis.version: Version 1.0
dmi.modalias: dmi:bvnTOSHIBA:bvrVersion4.80:bd06/23/2015:svnTOSHIBA:pndynabookR73/NW56E:pvrPR73NW56SUAE:rvnTOSHIBA:rndynabookR73/NW56E:rvrVersionA0:cvnTOSHIBA:ct10:cvrVersion1.0:
dmi.product.family: 0000000000
dmi.product.name: dynabook R73/NW56E
dmi.product.version: PR73NW56SUAE
dmi.sys.vendor: TOSHIBA
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.91-2
version.libgl1-mesa-dri: libgl1-mesa-dri 18.0.0~rc5-1ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx 18.0.0~rc5-1ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.19.6-1ubuntu4
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:18.0.1-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20171229-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-2