I realise the thread is old however I found it bu googling "Avast! annoying popups".
So it appears I'm not the only one, if you do google the above phrase there are loads of them. My biggest surprise was the way the admin guy treated the customer - have to say not very professional, don't know all the story, are you paid or a volunteer or just a forum helper. I'm amazed at the level of agression shown in such a short space of time. Th customer clearly annoyed by the apparent ruination of a product asks an almost rhetorical question and gets flamed.
Anyway I just thought I'd register to add my comments as I'm too getting a little fed up with the irritating 'motivational' popups. If you want to improve your product then just put them back how they were -simple or go the way of the other free-to-paid anvtiviruses.