I appreciate the thouroughness and legibility of your question, it really stands above some of the ones I've seen
Hmm... explorer.exe? And this is the one residing in c:\windows\ ? Well, if your AV didn't catch it, I'd assume it's just windows being sneaky again. Was it trying to connect to any particular address or ports? If it seems to be going for ports 137-139, then I'd guess it just has to do with your configuration of windows file sharing/NetBEUI/Netbios/That-buncha-stuff.
