I installed LION on an Imac 2011. 5 users have been setup for this Imac. There are no issues when 1user is logged on and using the imac. Once somebody else logs on, the second user, all looks ok but sometimes beachballs appear not matter what app you use, safari, chrome, finder, etc etc. There are no options to press any icons on screen, only the mouse moves around on screen. Pressing volume keys gives you the option to click on icons etc. But this is a bit frustrating. Nothing special is installed on this Imac. Only LION, nothing else. The Imac has 4GB default installed. Previously I even tried to setup parental controls, but that makes it even worse. Beachballs all around Does somebody else have noticed this?