Judging from christobzr's Xorg.0.log.old this is a duplicate of bug #358365, there is a full backtrace in that bug report.
-- [g41] When watching video, any window over video causes corrupt display and crash https://bugs.launchpad.net/bugs/353397 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
