Before you jump to conclusions, why don't you install zone alarm, its a personal fire wall from zone labs. its free and will let you know whenever anyone tries to access any service on your computer and stops them at the same time. If someone is pinging you ZA will give you the IP address of the culprit.
Don't forget, this is the time of the month for nimda and a new version on code red was just released. that can slow the whole show down.