Hi, i've recently been experiencing something funny with my Mac. Randomly, when i'm using it, typing usually, the screen rolls round (with the 'cube effect') and I am asked to enter my password to unlock the system. I've done a lot of Google searching and haven't found anything useful. More than anything I want to know what keys i'm pressing that cause this to happen to see if its some kind of awesome shortcut I don't know about. I would find one like this extremely useful. So what's going on? Is this a shortcut I don't know about? Any help would be appreciated. Cheers.