Pop up advertisement wont go away..

Hey everyone, not too sure where to put this so i decided to put it in here.
Anyway, i have two proxy sites and just recently i have been gettting a popup appear on each of the proxified pages (see image). I did have an account with Adbrite and i did have interstitial ads allowed, however i terminated the account as the ad code was playing havoc with my proxy script.
Surely this will not still be running and allowing these ads? I also checked to see if there are any running ads and there arn’t any, i also checked for spyware etc and some was found but this did not change anything.
http://www.imango.co.uk/v.php?id=44562popup ad.png
What could this be?
Any help greatly appreciated,
Thanks

Original post by convex7