Update: After a reboot the time before it happens again varies, from a couple of days to a few weeks.
I was able to have it go completely through the shutdown sequence - it took half an hour. -- Sparodically slow system clock https://launchpad.net/bugs/71023 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
