Hi, I have bought a Dell Dimension E520 on eBay and I put a new hard drive in it and installed windows xp and drivers from Dell's website and installed sp3, and then out of nowhere a black screen and then the dell logo appears and it boots up normal and then the same thing happens again and again and never stoppes. and it does it between 1-70 minutes. Is it bad or dirty ram or is it ready to be recycled. And the same dell xp disk used works with out a problem on a xps 400 and e310. Please help.