I have a Dell laptop that is running xp. If I turn it on and leave it, it is fine. If I try to run a program of any kind (scan, game, typing, browser), after about 5 minutes it locks up and gives off a constant beep - this beep is a repetitive short beep of the last sound before it locked up - so the tone/sound of the beep changes. I have to power off to get it going again. The computer is virus and malware clean. I've checked the memory. Any suggestions? Thanks.