RAM eka VGA eka test karanna.. ehema nethnam virus ekak...
did u recently tried to mess up with the registry?..
try to turn on in safe mode..
if u have a XP live CD; boot from it and delete all startup programs from the main XP registry.
try repair windows XP.
Mama RAM aka check kara boot karanna ba power 3 second wat na. Maga power supply aka pechchuna. Akat mama danma. Power supply aka wana computer akaka gahala check kara wada. Maga akata mokada karanna