I've just purchased a new Powerbook 15" which I'm very pleased with except for one thing: on rare occasions the screen will distort for a fraction of a second. It's happened to me quite a few times now and I've noticed chatter in other threads of people possibly seeing the same problem. On one occasion the sound also broke up, again for a fraction of a second. Perhaps we have a design flaw or chipset bug in our Powerbooks?