well, the first thing I would do is unplug your modem..., there are malicous program that will dail phone numbers...., so when you look at your next phone bill.......

I would download both Spybot and Adaware...
http://www.safer-networking.org/en/download/
http://www.lavasoftusa.com/support/download/ (huh they have a new SE version...)

Update there definitions, then scan your computer... and delete whatever comes up...

if this doesn't fix your problems, then I would download hijackthis
http://www.spywareinfo.com/~merijn/downloads.html

and then post your log in the hijackthis forum....

I hope this helps,
Byan