Wallpaper gets offset when logged in

As I don't know how to describe it, I have uploaded two pictures: http://imgur.com/a/MvSia
The Bug is in 15.04 and 15.10!
Primary monitor: 1920x1080, secondary: 1280x1024

I also experienced it when I plugged my laptop into my TV.

I am also not sure which package causes this, probably Lightdm?

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: xorg 1:7.7+7ubuntu4
ProcVersionSignature: Ubuntu 4.2.0-17.21-generic 4.2.3
Uname: Linux 4.2.0-17-generic x86_64
NonfreeKernelModules: fglrx
.tmp.unity.support.test.0:

ApportVersion: 2.19.1-0ubuntu3
Architecture: amd64
BootLog:
 [ OK ] Started Detect the available GPUs and deal with any system changes.
          Starting Light Display Manager...
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Tue Oct 27 23:04:10 2015
DistUpgraded: Fresh install
DistroCodename: wily
DistroVariant: ubuntu
DkmsStatus:
 fglrx-updates-core, 15.201, 4.2.0-17-generic, x86_64: installed
 vboxhost, 5.0.8, 3.19.0-31-generic, x86_64: installed
 vboxhost, 5.0.8, 4.2.0-17-generic, x86_64: installed
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 Advanced Micro Devices, Inc. [AMD/ATI] Tahiti XT [Radeon HD 7970/8970 OEM / R9 280X] [1002:6798] (prog-if 00 [VGA controller])
   Subsystem: PC Partner Limited / Sapphire Technology Device [174b:3000]
InstallationDate: Installed on 2015-06-19 (130 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
MachineType: MSI MS-7751
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-17-generic root=UUID=3f542aab-5392-4374-be7f-1a9017221366 ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/30/2013
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: V17.12
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: Z77 MPower (MS-7751)
dmi.board.vendor: MSI
dmi.board.version: 4.0
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: MSI
dmi.chassis.version: 4.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrV17.12:bd10/30/2013:svnMSI:pnMS-7751:pvr4.0:rvnMSI:rnZ77MPower(MS-7751):rvr4.0:cvnMSI:ct3:cvr4.0:
dmi.product.name: MS-7751
dmi.product.version: 4.0
dmi.sys.vendor: MSI
version.compiz: compiz 1:0.9.12.2+15.10.20151015-0ubuntu1
version.fglrx-installer: fglrx-installer N/A
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.64-1
version.libgl1-mesa-dri: libgl1-mesa-dri 11.0.2-1ubuntu4
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 11.0.2-1ubuntu4
version.xserver-xorg-core: xserver-xorg-core 2:1.17.2-1ubuntu9
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.2-1ubuntu1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.5.0+git20150819-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20150808-0ubuntu4
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11-1ubuntu3
xserver.bootTime: Tue Oct 27 13:18:21 2015
xserver.configfile: default
xserver.errors:
 open /dev/dri/card0: No such file or directory
 AIGLX error: failed to open /usr/X11R6/lib64/modules/dri/fglrx_dri.so, error[/usr/X11R6/lib64/modules/dri/fglrx_dri.so: cannot open shared object file: No such file or directory]
 AIGLX error: failed to open /usr/lib64/dri/fglrx_dri.so, error[/usr/lib64/dri/fglrx_dri.so: cannot open shared object file: No such file or directory]
 AIGLX error: failed to open /usr/X11R6/lib/modules/dri/fglrx_dri.so, error[/usr/X11R6/lib/modules/dri/fglrx_dri.so: cannot open shared object file: No such file or directory]
xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.17.2-1ubuntu9
xserver.video_driver: fglrx