I started up my Ubuntu 12.04 VM in VMWare Workstation 6. It has been a while, so some update messages popped up. Sure.
Afterwards, it rebooted and hung there. I should have left it; I force shutdowned and restarted. Now we are at a shell, where I can login, but nought else.
Sigh. Some Googling. Eventually find How to install Ubuntu Server – Precise Pangolin 12.04 .
In the section, “How to upgrade packages”, I found
$ sudo aptitude safe-upgrade
Hmm. Maybe the upgrade never finished. Give it a try.
Bam. 12.04 now running again. Better take a snapshot!