Ahhh, it was Wendy lol. We don't remember what program it was, but as it was likely something that was *installed*, it would not be a virus anyway.
Best bet is to look through all the plugins for your web browser to find any suspicious looking plugins about ads.
By the way, some software comes with 'bundled extras' and one thing I have seen them do before now is have a scrolling list of extras with everything you see unselected. It's only when you scroll down that you see all the sneakily hidden stuff that is selected by default. Dirty behaviour
Tom...