I've been having the same trouble. It seems erratic. I'm attaching the output of "lspci -vv" and /etc/X11/xorg.conf.
** Attachment added: "lspci.txt" http://launchpadlibrarian.net/23735801/lspci.txt -- switch user does not work https://bugs.launchpad.net/bugs/267828 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs