Comment 5 for bug 368594

Same (or similar) problem in Karmic Koala. When restarting or shutting down then message "System Policy prevents stopping the system when other users are logged in" appears. Then I have to write admin password. It is quite annoying for my children are unable shut down computer as they don't have admin privileges.

I have found same problem described here: http://ubuntuforums.org/showthread.php?t=1299948