Networking assistance request: Wired Xbox can't see Wireless PCs

[BvBPL]

I'm dealing w/ a home network issue and I am sort of at my wits' end here. So I figured I'd post the issue here in the thin hope that someone might have some advice.

We have two wireless laptops and a Xbox that is wired into my router. As of two weeks ago, the Xbox was able to see the wireless PCs. Now it can no longer see them, and I can't figure out why. To my knowledge, nothing has changed with the PCs, the Xbox, or the router.

However, if I plug a PC into the router via a CAT-5 cable, the Xbox can see that. I believe that this voids the idea that the issue is either with my Xbox or my Media Center settings on the computer.

I've tried resetting the Xbox's network config. No luck. I've cycled IGMP on my router settings, no dice there either. Called my ISP (that supplied the router) and they basically passed the buck.

Does anyone know why my wired Xbox would suddenly be unable to see the PCs. If anyone has any suggestions, I would be happy to hear them.

This link goes into more detail on the troubleshooting steps I've taken so far.

Any suggestions would be awesome.

If it helps any, it might be helpful to think of the issue as if I had a computer wired in that could not see the wireless computers.

Thanks