I downloaded BitDefender's Trial and when i restarted PC after installing it , my PC crashed and stopped working . i unplugged my PC and booted again many times but same thing happened. I have 256 MB RAM and processor speed is 1.70GHZ . Then i booted in safe mode and restored system with system restore . Although my PC is fine now but i want Bitdefender. Can anyone tell me why did my PC crash? (I am not having any other antivirus which can cause conflict) Also ,I might not be able to reply for 1 week because i have to go out of station this evening. Thank-you everyone.