Xorg assert failure: *** glibc detected *** /usr/bin/X: double free or corruption (!prev): 0x00000000036ef480 ***

Happens after I log out and log back in.

ProblemType: Crash
DistroRelease: Ubuntu 11.04
Package: xserver-xorg-core 2:1.9.99.901+git20110131.be3be758-0ubuntu3
ProcVersionSignature: Ubuntu 2.6.38-3.30-generic 2.6.38-rc4
Uname: Linux 2.6.38-3-generic x86_64
Architecture: amd64
AssertionMessage: *** glibc detected *** /usr/bin/X: double free or corruption (!prev): 0x00000000036ef480 ***
CrashCounter: 1
DRM.card0.DVI.D.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
DRM.card0.LVDS.1:
 status: connected
 enabled: enabled
 dpms: On
 modes: 1024x768 1024x768
 edid-base64: AP///////wAwriBAAAAAACMRAQOAHRV46m+VnFRMhyYhUFQAAAABAQEBAQEBAQEBAQEBAQEBZBkAQEEAJjAYiDYAH9cQAAAYKBUAQEEAJjAYiDYAH9cQAAAYAAAADwBhQzJhQygPAQAwZABTAAAA/gBMVEQxNDFFQ01CCiAgAOk=
DRM.card0.VGA.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
Date: Tue Feb 15 14:23:55 2011
DistUpgraded: Yes, recently upgraded Log time: 2010-12-30 12:18:19.227221
DistroCodename: natty
DistroVariant: ubuntu
ExecutablePath: /usr/bin/Xorg
GraphicsCard:
 Subsystem: Lenovo T61 [17aa:20b5]
   Subsystem: Lenovo T61 [17aa:20b5]
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Alpha amd64 (20100701)
MachineType: LENOVO 88986DG
PccardctlIdent:
 Socket 0:
   no product info available
PccardctlStatus:
 Socket 0:
   3.3V 32-bit PC Card
ProcCmdline: /usr/bin/X :1 -br -verbose -auth /var/run/gdm/auth-for-gdm-wUKiVJ/database -nolisten tcp
ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-3-generic root=UUID=4b488e8d-8ec5-4891-abc3-c1958b0fe161 ro vga=792 splash quiet splash vt.handoff=7
ProcKernelCmdLine_: BOOT_IMAGE=/boot/vmlinuz-2.6.38-3-generic root=UUID=4b488e8d-8ec5-4891-abc3-c1958b0fe161 ro vga=792 splash quiet splash vt.handoff=7
Signal: 6
SourcePackage: xorg-server
StacktraceTop:
 raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
 abort () at abort.c:92
 __libc_message (do_abort=2, fmt=0x7f7a1b6e5790 "*** glibc detected *** %s: %s: 0x%s ***\n") at ../sysdeps/unix/sysv/linux/libc_fatal.c:189
 malloc_printerr (av=<value optimized out>, p=0x36ef470) at malloc.c:6283
 _int_free (av=<value optimized out>, p=0x36ef470) at malloc.c:4795
Title: Xorg assert failure: *** glibc detected *** /usr/bin/X: double free or corruption (!prev): 0x00000000036ef480 ***
UserGroups:

dmi.bios.date: 11/14/2008
dmi.bios.vendor: LENOVO
dmi.bios.version: 7LETC5WW (2.25 )
dmi.board.name: 88986DG
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:bvr7LETC5WW(2.25):bd11/14/2008:svnLENOVO:pn88986DG:pvrThinkPadT61:rvnLENOVO:rn88986DG:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 88986DG
dmi.product.version: ThinkPad T61
dmi.sys.vendor: LENOVO
version.compiz: compiz 1:0.9.2.1+glibmainloop4-0ubuntu11
version.libdrm2: libdrm2 2.4.23-1ubuntu3
version.libgl1-mesa-glx: libgl1-mesa-glx 7.10-1ubuntu1
version.xserver-xorg: xserver-xorg 1:7.6~3ubuntu4
version.xserver-xorg-video-ati: xserver-xorg-video-ati N/A
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.14.0-1ubuntu7
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110107+b795ca6e-0ubuntu4