Originally Posted by TheBruce1

It could be hardware/software problem,since you have tried to install SP2 prior to being infected.You really need to install SP2 as without it leaves your system wide open to attack regardless of what antivirus/firewall you have installed.

You may want to think about formatting the disc and install SP2 on a clean machine,if you have your windows XP cd,if not is this a Dell or HP machine

Post a hijackthis log.