Was it a DOS attack?

[QUOTE= I seriously suggest scanning your machine for malware as I'm most certain you're infected with something.[/QUOTE]

Any suggestions regarding malware scanner? I tried the one provided with win XP. It found nothing.

I generally use more than one to be sure. Malwarebytes anti malware is a pretty decent one along with adaware and spybot. Might i also suggest getting a firewall that alerts you when there is a new connection coming in or going out. There are plenty free ones that work pretty well but its all up to preference. Comodo firewall and Sunbelt personal firewall are among some decent free firewalls.