compiz crashed with SIGSEGV in free()

Binary package hint: compiz

I was changing workspaces with Ctrl-Alt-<arrowkeys> when everything froze and compiz crashed.

ProblemType: Crash
DistroRelease: Ubuntu 11.04
Package: compiz-core 1:0.9.4git20110322-0ubuntu5
ProcVersionSignature: Ubuntu 2.6.38-7.38-generic 2.6.38
Uname: Linux 2.6.38-7-generic x86_64
NonfreeKernelModules: nvidia
.proc.driver.nvidia.gpus.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 270.30 Fri Feb 25 14:34:55 PST 2011
 GCC version: gcc version 4.5.2 (Ubuntu/Linaro 4.5.2-6ubuntu4)
Architecture: amd64
CompizPlugins: [core,bailer,detection,composite,opengl,decor,mousepoll,vpswitch,regex,animation,snap,expo,move,compiztoolbox,place,grid,gnomecompat,wall,ezoom,workarounds,staticswitcher,resize,fade,scale,session,unityshell]
CompositorRunning: compiz
CrashCounter: 1
Date: Sun Mar 27 14:11:15 2011
DistUpgraded: Fresh install
DistroCodename: natty
DistroVariant: ubuntu
DkmsStatus: nvidia-current, 270.30, 2.6.38-7-generic, x86_64: installed
ExecutablePath: /usr/bin/compiz
GraphicsCard:
 nVidia Corporation G86 [GeForce 8400 GS] [10de:0422] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: eVga.com. Corp. Device [3842:c733]
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha amd64 (20110201.2)
InstallationMedia_: Ubuntu 11.04 "Natty Narwhal" - Alpha amd64 (20110201.2)
JockeyStatus: xorg:nvidia_current - NVIDIA accelerated graphics driver (Proprietary, Enabled, In use)
MachineType: Intel To be filled by O.E.M.
ProcCmdline: compiz
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-2.6.38-7-generic root=/dev/mapper/Matterhorn-Root ro crashkernel=384M-2G:64M,2G-:128M quiet splash vt.handoff=7
ProcVersionSignature_: Ubuntu 2.6.38-7.38-generic 2.6.38
Renderer: Unknown
SegvAnalysis:
 Segfault happened at: 0x7f797d8688c3 <free+83>: lock cmpxchg %esi,(%rbx)
 PC (0x7f797d8688c3) ok
 source "%esi" ok
 destination "(%rbx)" (0x7f793400001f) not located in a known VMA region (needed writable region)!
SegvReason: writing unknown VMA
Signal: 11
SourcePackage: compiz
StacktraceTop:
 free () from /lib/x86_64-linux-gnu/libc.so.6
 ?? ()
 ?? ()
 ?? ()
 ?? ()
Title: compiz crashed with SIGSEGV in free()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm admin cdrom dialout libvirtd lpadmin plugdev sambashare
dmi.bios.date: 10/29/2009
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 4.6.3
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: To be filled by O.E.M.
dmi.board.vendor: Intel
dmi.board.version: To be filled by O.E.M.
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr4.6.3:bd10/29/2009:svnIntel:pnTobefilledbyO.E.M.:pvrTobefilledbyO.E.M.:rvnIntel:rnTobefilledbyO.E.M.:rvrTobefilledbyO.E.M.:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
dmi.product.name: To be filled by O.E.M.
dmi.product.version: To be filled by O.E.M.
dmi.sys.vendor: Intel
version.compiz: compiz 1:0.9.4git20110322-0ubuntu5
version.libdrm2: libdrm2 2.4.23-1ubuntu5
version.libgl1-mesa-glx: libgl1-mesa-glx 7.10.1-0ubuntu3
version.nvidia-graphics-drivers: nvidia-graphics-drivers N/A
version.xserver-xorg: xserver-xorg 1:7.6~3ubuntu11
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.0-0ubuntu4
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.14.0-4ubuntu4
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110107+b795ca6e-0ubuntu6