Now it could be a problem with my crappy crappy router. (Don't buy D-Link!) In fact, that seems likely, because I can successfully ping my other local computer. But does anyone know of anything else it might be? Known issues with ZoneAlarm, XP Pro SP1, or ethernet adapters onboard NVIDIA mobos?
Edit: Apparently it's DNS that stops working! I can get to Google by its IP address, but not by "google.com". I'm totally confused now. Ideas?
Edit 2, ~6:15pm EDT: What timing. Now my cable modem is entirely non-functional, and Comcast has a message on their tech support line that there are widespread problems. Yippee. This dialup is painful.