dave,
There have been many questions regarding RPC errors and Avast. I can't seem to find the central thread, but if you do a search here for "rpc", you will come up with much information.
The Remote Procedure Call initiated by Windows may be indicative of other security issues you might need to address.
Microsoft Knowledge Base has additional information on this subject.
I would ask the Avast team or our Global Moderator VLK to provide some technical guidance here.
In the meantime, I will try to locate any relavant articles and send them to you.
