I can confirm this bug after upgrading from lucid to maverick. Users with administrative rights used to be asked for their password when shutting down the system and other users were logged in. This doesn't work anymore.
Please note the following line in the .xsession-errors.old attached above: gnome-session[1745]: WARNING: Unable to stop system: Authorization is required ** Package changed: gnome-panel (Ubuntu) => gnome-session (Ubuntu) ** Changed in: gnome-session (Ubuntu) Status: Incomplete => Confirmed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/660120 Title: Cannot shutdown when multiple users are logged in -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs