Comment 36 for bug 456977

I wonder if running a newer upstream kernel would show the same problem.

https://wiki.ubuntu.com/KernelTeam/MainlineBuilds

Caveat: some other things may not work with such a non-customized-to-ubuntu kernel, but this can help diagnose some kernel-related problems. You will still be able to boot into Lucid kernels. There are instructions for removing the upstream kernel and libraries after you are done with the test. Removing the kernel will take it away from your grub2 boot menu.