I had done a repair, it did not work. In fact I tried two, one from the installed program itself instead of uninstalling, and one from the program installer which I downloaded to do the reinstall, neither worked.
I rebooted into Safe Mode, Administrator account, uninstalled Avast in Add/Remove Programs, then went to Program Files and removed the Awil Software folder, I ran RegScrubXP and CCleaner to clean the registry totally. Then I checked by eye. Once it was all gone I began a "clean" install from a downloaded installer. Then rebooted to Normal Mode and checked for updates, worked fine, so it was something that corrupted Avast. I have scanned since then and this system is clean.
Just updating the thread.