Thanks Eddy for the help on this issue, as I, you have spent a lot of time on this problem. I've been a keen user of Avast for a very very long time now and only ever had 2 issues in that whole time. But after trying the last suggestion from Eddy I finally gave up and uninstalled Avast. I have installed another product and no longer have the same issue. I'll give this issue a rest for the time being until I get the urge to reinstall avast again and run the support tool.
Thanks again for your efforts.