After reviewing the thread again, I believe that the virus is coming from outside your home network. I think that a friend or possibly just some one else on the same ISP as you is infected. The virus is trying to find the next system to pass itself on to by either randomly going through similar IP addresses on the same network or directly to an IP address found in the already infected machine.
Your scans are coming up clean, it only happens if you are connected to the network and just booted (which sends a lot of packets out to establish network links), and if you disconnect for a long period of time, the virus does not come back (yet). All of this points to the source being outside your computer. If your WHS is clean and your wife's system is clean (only other computer's on the system) then you may need to a) get another router (with different MAC ID - each internet enabled device has it's own unique MAC ID) or b) get your ISP involved to track the source down and disable it.
Your Norton products are protecting you correctly. The external virus keeps replacing what Norton has cured.