This command $ sudo dpkg -r --force-depends libgl1-mesa libgl1-dev libgl1-dri libglu1-mesa libglu1-mesa-dev mesa-common-dev mesa-utils $ sudo apt-get install -f
also fixed my problem, which appears to be the same as the one mentioned in this bug report. -- Can't calculate the upgrade with unofficial mesa/compiz packages https://launchpad.net/bugs/58424 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
