Comment 5 for bug 1072934

The error in the log files of the original bug reporter actually has to deal with running video drivers from a PPA and being unable to calculate the upgrade.

From main.log we see:

2012-10-30 00:48:07,741 DEBUG examining: 'deb http://ppa.launchpad.net/ubuntu-x-swat/x-updates/ubuntu precise main'
2012-10-30 00:48:07,743 DEBUG entry '# deb http://ppa.launchpad.net/ubuntu-x-swat/x-updates/ubuntu quantal main # disabled on upgrade to quantal' was disabled (unknown mirror)

And from apt.log we have:

Starting 2
Investigating (0) xserver-xorg-video-ati [ amd64 ] < 1:6.99.99+git20120928.e8cb0b72-0ubuntu0sarvatt~precise2 > ( x11 )
Broken xserver-xorg-video-ati:amd64 Depends on xorg-video-abi-12 [ amd64 ] < none > ( none )
  Considering xserver-xorg-core:amd64 34 as a solution to xserver-xorg-video-ati:amd64 1
  Removing xserver-xorg-video-ati:amd64 rather than change xorg-video-abi-12:amd64