This afternoon I got the part from Apple. I spent about 45 minutes replacing it. I didn't realize the mid-plane was basically the entire computer. I had to take the hard drive out, the DVD/CD drive out, the power supply out, and un-hook lots of wires. I put the new part in, put everything back in, and plugged everything back in and turned it on. Guess what? The exact same thing happened. It started up and then hung up at a certain point. I couldn't believe it. Then I started wondering if I simply try to re-install the system software back to the original. Since I got the computer Apple has put out an update and a few security updates. I've read on the boards that some of these updates have caused problems. So I did just that. I put the installation disc in and held down the C key. It started up great. I simply re-installed the system software and restarted. Works great. And I as far as I can see the only files I've lost are my book marks in Safari. I might be able to get that list from my back up tomorrow. I'm too tired to do any more tonight. I'm going to watch A Charlie Brown Christmas and then go to bed.