Further inspection revealed that the behavior was caused by display-manager.service refusing to shutdown in a timely manner, by systemd's definition. The process
still works out in the end, provided you wait long enough for the effected service to be forced to terminate by timeout. This is a public announcement, in the
event you experience a 'hang' during reboot or shutdown, that you should try waiting it out. The default timeout per service is 90 seconds, so it may take awhile.
If you want more details as to what is going on during this 'hang', you should boot without the 'splash' and 'quiet' boot arguments. Thank you.
Posted by ryuo - Sun, 19 Feb 2012 12:01:34 -0600