You say you had the Geek Squad update it. What exactly did they do?. I had a problem on my own recently and since i changed the PSU and Fan Unit it works great. Also about a year ago i had a problem as soon as i switched my PC on, it just shut down again and that was because i bought some extra Memory for it from PC World, turns out they gave me the wrong voltage and when i went back to them they didn't have a Scooby Doo so i purchase the correct type of Memory for my Pc from Crucial Memory online and that cured my problem then, so who knows maybe that is an issue for you also, depending on what the Geek Squad done.
If you find out what was done or have any other problems, e-mail me and i'll see what i can do to help. andy4u@live.co.uk
Andy
February 2009