Thank you for your reply norel.
I had previously tried all the steps you mention with repair as my first option, even a complete re-install as a last ditch attempt, but still WebRep is not showing as installed in FF and IE although it is showing on the Additional Protection page as my image indicates. I don't think that the WebRep feature particularly necessary and as Avast6 appears to be working in every other respect, I will probably leave it as it is without WebRep.
