Thanks Ken. Strangely enough, after way too much time fiddling with this, suddenly all the machines showed up in the network folder (however, residential gateway disappeared). Then my notebook (running Vista) showed only 2 machines. I'm wondering if this is my Linksys router acting weird. I'm going to leave my Windows 7 networking settings as is for now and see how it goes. Yes, I did set it up with IP6 and homegroup to begin with, but this is the only Windows 7 platform on the network. Still, prior to today, the network had been working great in both directions. Will report back anything conclusive.