My bug report was marked as a duplicate of this one. I cannot see the reference to it here so I post my bug report here since it contains the likely cause of your problem.
Binary package hint: x11-common Hi, dexconf overwrites xorg.conf without making a backup and without creating a backup copy when called with root privileges from the console. This can lead to data loss. Regards Rolf -- custom xorg.conf should not be overridden https://launchpad.net/bugs/57776 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs