After further testing I believe that Firefox as well as uTorrent cause the problems. This would in effect point to the internet connection. I a now using Firefox. AvastSvc at first went haywire, stopping the IM shield and then restarting it has calmed AvastSvc down and everything is now normal and quiet.
uTorrent was started last night and for the first hour or so did not disturb AvastSvc. This morning, however, AvastSvc was again doing its mysterious things, only returning to normal when I killed uTorrent.
Funny thing is, that none of the shields show any unusual activity when AvastSvc goes haywire. So what is it doing? Is it caught in an endless loop perhaps?
BW