I have a late 2009 macbook with Mac OS X 10.6.6. Since today morning, my mac is crashing with about everything. Every app I open up, browsers like Firefox or Safari, programs like Twitter. Even when I use the exposé. It just begins loading and that loading color circle appears, after that, everything stops. I try to restart Safari or even force to shut down programs, but the menus don't work. I don't know what to do, I use Macs for three years now, first time it happens to me. I'm using the guest account, I thought it would solve the problem, but eventually it crashes as well. Does anybody know possible causes?