Ubuntu frozen

[Gustav Goettlinger]

after several minutes the Computer is "freezing" and i cannot do anything anymore. No mouse and no keybord is working any more. It looks like the system is frozen!

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: xorg 1:7.7+13ubuntu3
ProcVersionSignature: Ubuntu 4.4.0-97.120-generic 4.4.87
Uname: Linux 4.4.0-97-generic x86_64
.tmp.unity_support_test.0:

ApportVersion: 2.20.1-0ubuntu2.10
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
Date: Wed Oct 18 20:50:19 2017
DistUpgraded: 2017-01-01 17:43:39,218 DEBUG icon theme changed, re-reading
DistroCodename: xenial
DistroVariant: ubuntu
GraphicsCard:
 Advanced Micro Devices, Inc. [AMD/ATI] Kaveri [Radeon R7 Graphics] [1002:130f] (prog-if 00 [VGA controller])
   Subsystem: Elitegroup Computer Systems Kaveri [Radeon R7 Graphics] [1019:9a18]
InstallationDate: Installed on 2016-06-22 (483 days ago)
InstallationMedia: Ubuntu 14.04.3 LTS "Trusty Tahr" - Beta amd64 (20150805)
MachineType: MEDION D3F3-EM
ProcEnviron:
 LANGUAGE=de_AT:de
 PATH=(custom, no user)
 LANG=de_AT.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-97-generic root=UUID=3ec08b5b-6ced-472a-91eb-d3df3b1cfe0b ro drm.debug=0xe vesafb.invalid=1 plymouth:debug nopat
SourcePackage: xorg
UpgradeStatus: Upgraded to xenial on 2017-01-01 (290 days ago)
dmi.bios.date: 06/09/2014
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: D3EMW08.106
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: D3F3-EM
dmi.board.vendor: MEDION
dmi.board.version: 1.0
dmi.chassis.type: 3
dmi.chassis.vendor: MEDION
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrD3EMW08.106:bd06/09/2014:svnMEDION:pnD3F3-EM:pvr1.0:rvnMEDION:rnD3F3-EM:rvr1.0:cvnMEDION:ct3:cvr:
dmi.product.name: D3F3-EM
dmi.product.version: 1.0
dmi.sys.vendor: MEDION
version.compiz: compiz 1:0.9.12.2+16.04.20160823-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.76-1~ubuntu16.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 17.0.7-0ubuntu0.16.04.2
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 17.0.7-0ubuntu0.16.04.2
version.xserver-xorg-core: xserver-xorg-core 2:1.18.4-0ubuntu0.7
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.10.1-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.7.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20160325-1ubuntu1.2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.12-1build2
xserver.bootTime: Wed Oct 18 20:48:37 2017
xserver.configfile: default
xserver.devices:
 input Power Button KEYBOARD, id 6
 input Video Bus KEYBOARD, id 7
 input Power Button KEYBOARD, id 8
 input Dell Dell USB Keyboard KEYBOARD, id 9
 input Logitech USB Optical Mouse MOUSE, id 10
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.18.4-0ubuntu0.7
xserver.video_driver: radeon