after Welcome messgege and loading windows xp, the screen goes into gray or other colors, i mean once it is gray, the other times it is black, blue, red or green. i cant restart it, when restart system manually , it goes to stand by and the hard lamp is red all the time, so i have to turn the system off. I can go to safe mode and work in safe mode but not in normal windows. I need your help please. what's the problem?