I just got my 17" MBP 2.8 ghz on Thursday. I put Snow Leopard on it Friday. I've noticed that it keeps freezing up every now and then. The whole system just stops for a few seconds, iTunes stops playing, and then the pinwheel spins. Is this Snow Leopard or the computer itself? It's driving me crazy! It goes away after a little bit, but it keeps coming back--on both graphics cards.