Just got an iMac yesterday. Today when I turned on the iTunes screen saver, the screen turned black, and wouldn't respond. I held the power button for several seconds until it turned off, and then turned it back on. Everything was ok until I went to configure the screen savers. As soon as I picked the first one, the preview screen turned gray, and the wheel started spinning. I used force quit on it, and tried loading a different screen saver, and same thing happened. What's going on?