ok, those logs clearly show that xorg is crashing, could, you open a new bug using "ubuntu-bug", selecting Display and following the questions?
** Changed in: totem (Ubuntu) Status: Incomplete => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/752405 Title: totem sometimes restarts gdm while playing videos -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs