OK, so that was the reason! I've now run "sudo aptitude remove libgl1-mesa-dri" which downgraded to 6.4.1.-0ubuntu8.
This seemed to do trick! Thank you! -- Can't install 'ubuntu-desktop' https://launchpad.net/bugs/63205 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
