Interesting networking problem

[Prisoner_Number_Six]

Networking between two computers either using a crossover cable or a switchbox is extremely straightforward, as long as the setup is correct-- workgroup names, file and print sharing, and so on. Plug it in and set it up, and it works or it's usually a hardware problem (Linksys routers have a high out-of-the-box failure rate, for example).

My "unsolvable" scenario is this: I have an XP machine and a Win98 machine, both of which network perfectly with other computers (I tested them both with a laptop and a crossover cable, and separately with a switch box and normal patch cables I tested on different machines before hooking it up to these machines). However, they WILL NOT TALK TO EACH OTHER.

I've checked everything up to and including firewalls, etc. They simply do not see each other, although both separately will instantly hook up to other networks, including my home system (said network using an AirLink router, a couple switch boxes and a wireless access point to hook up to Comcast. It consists of both XP and Win2K machines).

I'm stumped. Oh, btw, the Win98se machine is a fresh install on a scrubbed hard drive. All drivers are present and all cards have been tested.

Any clues for someone who is obviously missing something obvious (that is probably doing everything short of reaching out and slapping my face)? I know when I figure it out it'll be a real Duh moment, but I never said I knew everything about everything.