https://bugs.freedesktop.org/show_bug.cgi?id=73848
--- Comment #16 from Marti Raudsepp marti@juffo.org --- (In reply to comment #15)
If you disable acceleration (add Option "NoAccel" "true" to the device section of your xorg config) do you still get the problems? It's most likely some issue related to the 3D engine set up in mesa.
You're right, NoAccel true also fixes this issue.