So that's what happened to my computer...
I have never use any file-sharing software before (napstar, kazaa), and a couple of weeks ago I was bored and thought I would try out kazaa lite... After I installed it, I started having trouble with the internet... some sites would work fine while others couldnt be reached... Initially I thought it was my ISP, but after a while I said 'fxck it' and formatted my PC... Now it's working fine again (of course I didnt install kazaa anymore), and I would never install any file-sharing software again...