MostOfMyMac.com

When attempting to restart or shut down your computer in Mac OS X v10.5 through v10.5.8 (while multiple users are logged in using Fast User Switching), you will receive this alert: “There are currently logged in users who may lose unsaved changes if you restart this computer.” To proceed, you must enter a name and password belonging to an administrator account. However, if you enter a valid administrator user’s name and password, then click on the Restart or Shut Down button, you will receive this message: “Invalid user name or password.