I've recieved a number of emails from webmasters on other sites who are having the same issue and finding this thread via google. If you are having the problem it turned out to be a flash file located:
http://www.wdwinfo.com/js/swfobject.js
We have used this file for a number of years, AVG just decided it didn't like it.
Since flash is unneccesary for this site we just removed it