Comment 3 for bug 551797

You need to enable the xorg-edgers PPA again, sudo apt-get install ppa-purge and then sudo ppa-purge xorg-edgers to remove the old xorg-edgers karmic packages that were left behind after upgrading. Then you can reenable xorg-edgers and you will have to manually reinstall xserver-xorg-video-all that is missing because of the screwed up upgrade. The dialog hanging is a dupe of the bug I marked on here otherwise though.