Comment 11 for bug 545039

One useful thing to try would be to trace the graphics driver stack to determine what is going on. Please run the following on the latest Ubuntu kernel:

$ sudo sh -c "echo ':mod:i915 :mod:drm :mod:drm_kms_helper check_hung_uninterruptible:traceoff:' > /sys/kernel/debug/tracing/set_ftrace_filter"
$ sudo sh -c "echo 1 > /sys/kernel/debug/trace/tracing_enabled"
$ sudo sh -c "echo 1 > /sys/kernel/debug/trace/tracing_on"
$ sudo sh -c "echo function_graph > /sys/kernel/debug/trace/current_tracer"

Wait for the issue to occur, then

$ bzip2 -c /sys/kernel/debug/tracing/trace > ftrace.bz2

Finally, attach the trace file to this bug.

Thanks