I have a black Macbook Core 2 Duo, bought in December of '05, and recently Mac OS X has been quitting on me. It usually happens when I'm watching a video online, and the video starts skipping, and when I try and use the mouse it skips as well. So does audio. Then the monitor dims and a message appears telling me that I have to restart computer. When I restart it, it informs me that Mac OS X force quit. Help?