Well Pebbles
It does seem that you have a virus or worm, despite what your AV says.
So, I've got a couple of questions for you:-
1) What AV do you have?
2) Have you recently updated your AV with the latest updates?
To be honest, question 2) is the most crucial because non-updated AVs are next to useless.
At this stage, I would suggest that you do an online scan of your PC, if possible, because there is something on your PC that is being missed. There are three free online scanners that I know of (you can "google" for more if you want to):-
Online Anti-Virus Scanners
Trend Micro HouseCall - Free Online Virus and Spyware Scan - Trend Micro USA
[url=http://www.kaspersky.com/virusscanner****** Virus Scan - Kaspersky Lab[/url]
Symantec Security Check
Good Luck
UK Bob
MODERATOR HELP NEEDED - The self-censoring forum software has messed up my "Kespersky" URL, even though the preview was OK, can a Moderator please re-form my URL, i.e. remove the stars.