It sounds like spyware, all the tools you have are very good ones for removing such things. If you're running Xp there may be a missing security update for IE possibly. Sometimes a system restore to an earlier time before you had the problem will work to rid you the problem, I'm sure others out there will know more about this than me, but make sure all your anti virus/ spyware progs' are up to date.
Personally, I keep using new tools to rid till I find the one that works.....maybe worth a go?
Terry.
April 2006