It would be interesting to find out anyways. I had a beef with a friend when relaying the information about AVG since he was asking about the latest version with him blabbering that Vista was the problem? He is simply too lazy!
The user32.dll file has been a common system file in different versions to start with. Like I was starting to describe before it looks like a file you think would be something for user accounts when it's actual purpose is to allow various programs to have a gui to work with for text as well as user input and Windows management.
Hey Mak the article there points mostly at XP not so much with Vista as being the version this supposedly hammers the most. Grisoft moved fast to see that corrected so I wouldn't expect much. I only temporarily disabled AVG earlier today and haven't seen one iota of trouble since the update was out over the weekend and today is... wednesday!