As you can see, I have Limewire, a Peer2Peer file sharing software, so I think I must've downloaded some corrupt file. I deleted all recently download files in an attempt to rectify the problem but still nothing. This is NOT the first time I've had this problem. The other times I had to have my father-in-law come and delete the whole computer (can't remember what this whole process is called) - you would think I have learned my lesson. I'm hoping that it doesn't come down to this because it's a pain in the neck... for him.
Also, is there any way I can identify exactly what the culprit for this problem is and where it exists so that I can deal with it if it happens again?