Comment 20 for bug 295756

Phew.... well, since I'm currently studying for a test, and I only got some clues on what's wrong here but no definete idea, I gotta leave you here until the weekend, sry for that.
I've read on changing from onboard to external graphics device that it is important to change the busid of the device in use in the xorg.conf. Maybe you can get some info in wikis or board on your problem, or I'd recommend to talk to the guys on the Ubuntu IRC https://help.ubuntu.com/community/InternetRelayChat

Good luck for now!