Avast version 2014.9.0.2021 free version.
I had tried Kaspersky before. I think I get rid of everything except maybe some registry entries.
No, I didn't install anything else recently, nor since. And the problem was happening before I had started any applications, so I don't think it wasn't anything else. Anyhow, stopping Avast solved the problem.
Weird: Now it is working fine. I'm not sure why, but I did uncheck all 3 options under Active Protection. I assume that there was some bug in one of the Avast updates that was causing the problem, and that was subsequently fixed.
Anyhow, I guess it doesn't matter any more. Thanks for following up my message.
-- Tom