Thanks for the ideas folks. It turned out to be the AVG Outlook Add In.
To disable it, I had to start OUtlook as an admininstrator, by Right CLicking the Outlook Icon on my desktop, then selecting Tools - Trust Centre - Add-ins - COM Add-ins - Go, and then deselecting the AVG add-in.
So now i'm without that Add-in protecting my email. I can live with that.
Hope this string helps someone else.
Dan