This problem seems to be related to KMS in 2.6.32: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/549989 (several similar reports can be found on other distro's bugtrackers) Either disabling KMS entirely (i915.modeset = 0 in /etc/defaults/grub) or disabling the powersave option (i915.powersave = 0) solves the problem. It looks like a kernel bug in 2.6.32. Please feel free to reassign or close this bug report as appropriate.