I just wanted to say thanks to Ian Ferguson for describing the problem and pointing me to the solution here, ubradford for figuring out a solution which has been annoying me for months, and stevo1982 for the password fix. My Ubuntu 10.04 install now reboots and shuts down cleanly and immediately!

I do have a different problem now though: none of my CIFS mounted Windows shares listed in fstab are being mounted at startup anymore. If I manually run mount -a they all mount fine. Any ideas why that may have changed?