Do you have any other antivirus installed in your computer?
Did you have in the past? Which one?
RPC error is generally related to other antivirus present or, at least, firewall blocking. Do you use a firewall? Which one?

Anyway, RPC error is most likely correct by this procedure:
Go to Control Panel > Add/Remove programs > avast! antivirus > Remove
Then choose Repair function in the pop up window (Repair).