I encountered this bug as well. I was running the fglrx driver and the upgrade to 7.1.1 broke it. I figured I'd just edit the /etc/X11/xorg.conf file to use ati instead, but it came up with the version mismatch error and wouldn't load. It turns out that you can fix it by upgrading xserver-xorg-video-ati by hand. I would have expected this to be automatic and perhaps something is broken with the dependencies? The vesa driver was the same way. I had to "apt-get install xserver-xorg-video-vesa" before it would not bomb out on a version mismatch.
-- Dependency relationships allow core and drivers to be out of sync https://launchpad.net/bugs/54225 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
