New and need help with an annoying thing!

Hi, you'll have to excuse me for asking help in my first post here - but I'm getting really annoyed now.

Somehow I have picked up some code thing that follows me around in vBull forums, but only in Firefox and on this pc. Everything is fine if I use IE or my laptop

I've cleared cookies/history in both browsers, done CCleaner and Avast but it's found nothing at all, tried Googling it and found nothing there.

Can anyone help at all.............please bear in mind despite owning a couple of vBull sites, I'm no techie whizz so need simple answers

--------------- Added [DATE]1284064908[/DATE] at [TIME]1284064908[/TIME] ---------------

Oh God okaaaaaaaaay that's weird, it's not following me on here!!!!

This is what's following me about in my posts and pm's on 3 other vBull forums;

21688df7-c6c5-4c82-bb9b-70dd51f41d70
1.03.01

--------------- Added [DATE]1284066288[/DATE] at [TIME]1284066288[/TIME] ---------------

No worries now thanks!!
Somebody has just helped me, it's an extension in Firefox called Yontoo!