I have the same problem here with a Feisty-machine with auto-mounted CIFS filesystem. The reason for this seems to be that dbus, which controls NetworkManager is shut down at /etc/rc0.d/K20dbus which is run before /etc/rc0.d/S31umountnfs.sh
-- Unmount of remote CIFS shares fails with timeout on system shutdown https://launchpad.net/bugs/90795 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
