@swahil
what error are you getting on the screen once you start the system? Do you get the blue screen on start too? If yes, then your windows xp is corrupted because of the video driver. It has not much to do with virus. If you don't see anything, check for the ram and other parts. Some part might be loose, or needs some cleaning up. In any case, as munneraja mentioned, install windows again, and use a free antivirus, to secure your pc, and make sure to update antivirus every week.
__________________
|