Upon request I am posting my Xorg.0.log in this comment to help further diagnose the issue.
** Attachment added: "Xorg.0.log" http://librarian.launchpad.net/7058779/Xorg.0.log -- 20070330 Xubuntu AMD64 upgrade - loss of video https://launchpad.net/bugs/99048 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
