Xorg crashed with SIGABRT

Unknown which user action contributed to this

ProblemType: Crash
DistroRelease: Ubuntu 14.04
Package: xserver-xorg-core 2:1.15.0-1ubuntu7
ProcVersionSignature: Ubuntu 3.13.0-18.38-generic 3.13.6
Uname: Linux 3.13.0-18-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.13.3-0ubuntu1
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
CrashCounter: 1
Date: Fri Mar 21 11:48:03 2014
DistUpgraded: 2014-01-31 23:52:38,971 DEBUG enabling apt cron job
DistroCodename: trusty
DistroVariant: ubuntu
DkmsStatus:
 virtualbox, 4.3.6, 3.13.0-17-generic, x86_64: installed
 virtualbox, 4.3.6, 3.13.0-18-generic, x86_64: installed
ExecutablePath: /usr/bin/Xorg
ExtraDebuggingInterest: Yes
GraphicsCard:
 NVIDIA Corporation G84GL [Quadro FX 1700] [10de:040f] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: NVIDIA Corporation Device [10de:049a]
InstallationDate: Installed on 2011-12-04 (838 days ago)
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111011)
MachineType: Dell Inc. Precision WorkStation T7400
ProcCmdline: /usr/bin/X -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
ProcEnviron:

ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-18-generic root=UUID=cea7b9f7-43ba-442c-ad69-638a70ffde6d ro quiet splash vt.handoff=7
Signal: 6
SourcePackage: xorg-server
StacktraceTop:
 ?? () from /usr/lib/xorg/modules/libexa.so
 ?? () from /usr/lib/xorg/modules/libexa.so
 ?? () from /usr/lib/xorg/modules/libexa.so
 ?? () from /usr/lib/xorg/modules/libexa.so
 ?? () from /usr/lib/xorg/modules/libexa.so
Title: Xorg crashed with SIGABRT
UpgradeStatus: Upgraded to trusty on 2014-01-31 (48 days ago)
UserGroups:

dmi.bios.date: 01/31/2008
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A01
dmi.board.name: 0RW199
dmi.board.vendor: Dell Inc.
dmi.chassis.type: 7
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA01:bd01/31/2008:svnDellInc.:pnPrecisionWorkStationT7400:pvr:rvnDellInc.:rn0RW199:rvr:cvnDellInc.:ct7:cvr:
dmi.product.name: Precision WorkStation T7400
dmi.sys.vendor: Dell Inc.
version.compiz: compiz 1:0.9.11+14.04.20140310-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.52-1
version.libgl1-mesa-dri: libgl1-mesa-dri 10.1.0-1ubuntu1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 10.1.0-1ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.15.0-1ubuntu7
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.8.2-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.3.0-1ubuntu3
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.910-0ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.10-1ubuntu2
xserver.bootTime: Fri Mar 21 11:48:52 2014
xserver.configfile: default
xserver.devices:
 input Power Button KEYBOARD, id 6
 input Power Button KEYBOARD, id 7
 input PixArt USB Optical Mouse MOUSE, id 8
 input Dell Dell USB Keyboard KEYBOARD, id 9
 input sonixj KEYBOARD, id 10
xserver.errors:
 Failed to load module "nvidia" (module does not exist, 0)
 Failed to load module "nvidia" (module does not exist, 0)
xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.15.0-1ubuntu7
xserver.video_driver: nouveau