many thanks for the info. I thought I would try an upgrade first as I recently re-installed vista on my 64bit machine, and it is impossible to get it any cleaner than it is, or more up to date. Hence worth a try.
If it bellies-up on the up-grade then a clean install would have to be done.
I asked the same question recently and had this reply from Sea Urchin: For AVG - open user interface and double-click Resident Shield - uncheck box beside Resident Shield Active and click Save Changes. It seems to work