xorg crashes 1 time in 5 when attempting to sleep

I am running xubuntu 12.04 on a Thinkpad X301. Since I first installed 12.04 a few months ago, everything worked fine for a couple of months. But a few weeks ago (i.e. early July 2012), I started getting xorg crashes.

The crashes happen when the computer is attempting to sleep (suspend, not hibernate), either because I closed the lid or because I left it on long enough for sleep to kick in automatically. It happens about 1 time in 5 that sleep is attempted. I get returned to the login screen. Sleep does not complete. The flashing moon light continues to blink. I can log in again and continue, but nothing works properly... no wireless, docky will not launch, everything is very slow, etc.

These frequent crashes make xubuntu 12.04 completely unusable. I hope that a solution can be found soon.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: xorg 1:7.6+12ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-26.41-generic 3.2.19
Uname: Linux 3.2.0-26-generic x86_64
ApportVersion: 2.0.1-0ubuntu11
Architecture: amd64
Date: Sun Jul 22 06:11:00 2012
InstallationMedia: Xubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
ProcEnviron:
 LANGUAGE=en_US:en
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
---
ApportVersion: 2.0.1-0ubuntu11
Architecture: amd64
DistroRelease: Ubuntu 12.04
InstallationMedia: Xubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
Package: xorg 1:7.6+12ubuntu1
PackageArchitecture: amd64
ProcEnviron:
 LANGUAGE=en_US:en
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 3.2.0-26.41-generic 3.2.19
Tags: precise
Uname: Linux 3.2.0-26-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin netdev plugdev sambashare sudo