Xorg crashed with SIGABRT in dixGetPrivate()

[Andy Whitcroft]

screen saver locked up with cursor as ->, then this occured when i was switching to vt1 to restart unity.

ProblemType: Crash
DistroRelease: Ubuntu 14.04
Package: xserver-xorg-core 2:1.15.0-1ubuntu7
ProcVersionSignature: Ubuntu 3.13.0-18.38lp1293549v201403181544-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
Date: Tue Mar 18 22:15:33 2014
DistUpgraded: 2013-11-10 13:06:03,584 DEBUG enabling apt cron job
DistroCodename: trusty
DistroVariant: ubuntu
DkmsStatus:
 virtualbox, 4.3.6, 3.13.0-16-generic, x86_64: installed
 virtualbox, 4.3.6, 3.13.0-17-generic, x86_64: installed
ExecutablePath: /usr/bin/Xorg
ExtraDebuggingInterest: Yes
GraphicsCard:
 Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 08) (prog-if 00 [VGA controller])
   Subsystem: Intel Corporation Device [8086:2211]
InstallationDate: Installed on 2013-06-20 (271 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Alpha amd64 (20130618)
MachineType: Intel Corporation 2012 Client Platform
ProcCmdline: /usr/bin/X -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
ProcEnviron:

ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.13.0-18-generic root=UUID=bc3aa227-2363-4fb5-a7af-77fd6d275703 ro quiet splash vt.handoff=7
Signal: 6
SourcePackage: xorg-server
StacktraceTop:
 ?? ()
 ?? ()
 ?? ()
 xf86VTSwitch ()
 WakeupHandler ()
Title: Xorg crashed with SIGABRT in xf86VTSwitch()
UpgradeStatus: Upgraded to trusty on 2013-11-10 (128 days ago)
UserGroups:

dmi.bios.date: 07/30/2012
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: ACRVMBY1.86C.0094.P02.1207301240
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: Latexo FFRD
dmi.board.vendor: Intel Corporation
dmi.board.version: To be filled by O.E.M.
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 9
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrACRVMBY1.86C.0094.P02.1207301240:bd07/30/2012:svnIntelCorporation:pn2012ClientPlatform:pvrTobefilledbyO.E.M.:rvnIntelCorporation:rnLatexoFFRD:rvrTobefilledbyO.E.M.:cvnToBeFilledByO.E.M.:ct9:cvrToBeFilledByO.E.M.:
dmi.product.name: 2012 Client Platform
dmi.product.version: To be filled by O.E.M.
dmi.sys.vendor: Intel Corporation
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: Tue Mar 18 22:15:39 2014
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 6107
 vendor COR
xserver.version: 2:1.15.0-1ubuntu7

[Apport retracing service (apport)]

StacktraceTop:
 dixGetPrivate (key=<optimized out>, privates=0x7f07442e0c38) at ../../../../include/privates.h:137
 dixLookupPrivate (key=<optimized out>, privates=0x7f07442e0c38) at ../../../../include/privates.h:167
 dixLookupScreenPrivate (pScreen=0x7f0743d7f190, key=<optimized out>, privates=0x7f07442e0c38) at ../../../../include/privates.h:216
 xf86SetCursor (pScreen=pScreen@entry=0x7f0743d7f190, pCurs=0x7f07442e0c20, x=x@entry=1429, y=y@entry=0) at ../../../../hw/xfree86/ramdac/xf86HWCurs.c:134
 xf86CursorSetCursor (pDev=0x7f0743e2b8c0, pScreen=0x7f0743d7f190, pCurs=0x7f07442e0c20, x=1429, y=0) at ../../../../hw/xfree86/ramdac/xf86Cursor.c:360