Comment 89 for bug 1384342

So much for that guess. Recommend you report the bug upstream and try reproducing it in a later kernel (for instructions see http://askubuntu.com/questions/119080/how-to-update-kernel-to-the-latest-mainline-version-without-any-distro-upgrade and you can get the latest drm-intel-nightly packages from http://kernel.ubuntu.com/~kernel-ppa/mainline/drm-intel-nightly/ )