I have basically the same setup, Belkin Wireless-N router, Windows Vista 64-bit Home Edition, and was experiencing this problem. I turned off my router's firewall, and the problem is resolved. Also, I only recently got this new router, was using a Linksys router previously and never had the problem, so pretty sure it is the router itself. Anyone who finds a specific port or anything like that we can forward to download mods while leaving the firewall turned on, information would be greatly appreciated!