Xorg crashed with SIGSEGV in drm_intel_bo_unpin()

Xorg crashed with SIGSEGV in drm_intel_bo_unpin

ProblemType: Crash
Architecture: i386
CrashCounter: 1
DistroRelease: Ubuntu 9.04
ExecutablePath: /usr/bin/Xorg
Package: xserver-xorg-core 2:1.6.0-0ubuntu8
ProcAttrCurrent: unconfined
ProcCmdline: /usr/X11R6/bin/X :0 -br -audit 0 -auth /var/lib/gdm/:0.Xauth -nolisten tcp vt7
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
ProcVersion: Linux version 2.6.28-11-generic (buildd@palmer) (gcc version 4.3.3 (Ubuntu 4.3.3-5ubuntu4) ) #39-Ubuntu SMP Thu Apr 2 03:00:35 UTC 2009
Signal: 11
SourcePackage: xorg-server
StacktraceTop:
 drm_intel_bo_unpin () from /usr/lib/libdrm_intel.so.1
 ?? () from /usr/lib/xorg/modules/drivers//intel_drv.so
 i830_crtc_dpms_video ()
 ?? () from /usr/lib/xorg/modules/drivers//intel_drv.so
 ?? () from /usr/lib/xorg/modules/drivers//intel_drv.so
Title: Xorg crashed with SIGSEGV in drm_intel_bo_unpin()
Uname: Linux 2.6.28-11-generic i686
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