One thing I've noticed which may help reproduce this. I'm currently logging in without a password. The errors start happening when the password manager (seahorse) starts popping up dialogues to ask for passwords.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/748636 Title: WARNING: at /build/buildd/linux-2.6.38/drivers/gpu/drm/radeon/radeon_fence.c:248 radeon_fence_wait+0x36f/0x3e0 [radeon]() -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs