Forwarding this bug from Ubuntu reporter Matthew Thomas:
http://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/981304

[Problem]
Window switching leads to blank display and gpu lockup.  Occurred only one time on a fresh installation of ubuntu precise.  No other reports of users seeing this misbehavior or having this IPEHR code.

[Original Description]
Possibly related to ccsm... I installed compizconfig-settings-manager to enable windows switching, hit alt-tab a couple of times, then blank display and no keyboard requiring hard reboot.

ProblemType: Crash
DistroRelease: Ubuntu 12.04
Package: xserver-xorg-video-intel 2:2.17.0-1ubuntu4
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic-pae 3.2.14
Uname: Linux 3.2.0-23-generic-pae i686
.tmp.unity.support.test.0:
 
ApportVersion: 2.0.1-0ubuntu2
Architecture: i386
Chipset: i965gm
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
Date: Fri Apr 13 20:55:53 2012
DistUpgraded: Fresh install
DistroCodename: precise
DistroVariant: ubuntu
DkmsStatus: virtualbox, 4.1.12, 3.2.0-23-generic-pae, i686: installed
DuplicateSignature: [i965gm] GPU lockup  render.IPEHR: 0x11229000 Ubuntu 12.04
ExecutablePath: /usr/share/apport/apport-gpu-error-intel.py
ExtraDebuggingInterest: Yes, if not too technical
GpuHangFrequency: This is the first time
GpuHangReproducibility: I don't know
GpuHangStarted: Today
GraphicsCard:
 Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (primary) [8086:2a02] (rev 0c) (prog-if 00 [VGA controller])
   Subsystem: Lenovo T61 [17aa:20b5]
   Subsystem: Lenovo T61 [17aa:20b5]
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha i386 (20120320)
InterpreterPath: /usr/bin/python2.7
MachineType: LENOVO 7762WU2
PccardctlIdent:
 Socket 0:
   no product info available
PccardctlStatus:
 Socket 0:
   no card
ProcCmdline: /usr/bin/python /usr/share/apport/apport-gpu-error-intel.py
ProcEnviron:
 
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-23-generic-pae root=UUID=25a606c6-1a22-4194-a052-4aab8dee4773 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 xserver-xorg             1:7.6+12ubuntu1
 libdrm2                  2.4.32-1ubuntu1
 xserver-xorg-video-intel 2:2.17.0-1ubuntu4
SourcePackage: xserver-xorg-video-intel
Title: [i965gm] GPU lockup  render.IPEHR: 0x11229000
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:
 
dmi.bios.date: 11/27/2008
dmi.bios.vendor: LENOVO
dmi.bios.version: 7SET36WW (1.22 )
dmi.board.name: 7762WU2
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr7SET36WW(1.22):bd11/27/2008:svnLENOVO:pn7762WU2:pvrThinkPadX61Tablet:rvnLENOVO:rn7762WU2:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 7762WU2
dmi.product.version: ThinkPad X61 Tablet
dmi.sys.vendor: LENOVO
version.compiz: compiz 1:0.9.7.6-0ubuntu1
version.libdrm2: libdrm2 2.4.32-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 8.0.2-0ubuntu3
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 8.0.2-0ubuntu3
version.xserver-xorg-core: xserver-xorg-core 2:1.11.4-0ubuntu10
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.7.0-0ubuntu1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~git20111219.aacbd629-0ubuntu2
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.17.0-1ubuntu4
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20111201+b5534a1-1build2