|Okay, I hope someone is still around, I wasn't home until tonight.|
I turned off the firewall and tried to ping the router, all requests still timed out.
When I did tracert 18.104.22.168, all 30 attempts timed out. Tracert yahoo.com gave me "Unable to resolve target system name yahoo.com"
I tried to ping my machine from a second computer attached to the router, and all four requests timed out. I CAN ping the router from this second computer, though.
I set up the network here, and I've had to re-install an OS and the drivers for this same network card, and I've never encountered such a baffling problem. I am starting to think it is the card itself!
Thanks for all your help!