This modest little announcement ....
... does not do justice to the amount of work & dedication that Mike put into this. I reported the problem on Monday which could not be repeated on any of the systems that Mike and others were running.
At his request, I tried various things and tried to say exactly what I did to create the lock-up. However, it was his efforts & patience in examining the program code to find a tiny portion that Grisoft AVG running on XP did not like. This was despite the fact that the QU directories were excluded form AVG Resident Shield.
I don't know if others have noticed a problem or not, it could help them too.
This is a public "Thank you" to Mike for his excellent personal service. 
Terry