Ok, this is just bizarre.
I have a single wifi access point in my house. My main computer, running Win7 Ultimate x64, can't seem to get to anywhere on the internet. I can ping my router, I can access my printer's setup web page, but I can't access the router's administration page.
A Windows Virtual PC VM (running Win 7 Ultimate x86) on this same physical machine, can get to the internet just fine. It can't get to my router's administration page, but it gets everywhere else ok.
Do I have goblins?