https://bugs.freedesktop.org/show_bug.cgi?id=39317
--- Comment #5 from Jeremy Murphy jeremy.william.murphy@gmail.com 2011-09-05 04:29:58 PDT --- I presume that it happened in a recent git pull of mesa, BUT it might also have been upgrading xorg-server from 1.10.2 to 1.10.4. I actually tried to downgrade mesa in order to confirm what fixed it but ran into a problem. If you're interested I'll persist and get an answer for you.