...very interesting...
After I repeated all the previous steps, I then ran a Norton sweep on the registry - tried it again, but still no success. :'(
Finally, in desperation I decided to try installing the old Avast32 - Avast 3
It installed and automatically updated to avast 4. I did the settings, then the required reboot - and....
...be still my heart - avast loaded! I was never so happy to see that spinning blue "a" ball!
I checked and I do have the latest program and vps.
Go figure! Thanks to all who responded, and hopefully this will continue to behave.