Sounds like you have an X freeze rather than a crash. You probably want this:
https://edge.launchpad.net/~ubuntu-x-swat/+archive/x-freeze-test
backtraces don't give much useful info with freezes.
** Changed in: xorg-server (Ubuntu)
Status: Incomplete => Invalid
--
Apport doesn't collect xorg crash informations
https://bugs.launchpad.net/bugs/349945
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
--
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
