Windows Media Center "Extender Not Found"

I have windows vista ultimate connected to a netgear wireless N router
WNR834M. When I first formatted my pc and connected my desktop to the
network i saw the message come up that an extender was found. I was able to
setup Windows Media Center and the Xbox so that i could see music, pics, and
vids with no problem. Two days later I am now unable to connect my 360 and
my desktop pc together. I have windows onecare as my firewall so this is not
the issue. I have upnp enabled on the router so that is not the problem
either. i have tried enabling windows firewall in conjunction with the
onecare firewall, and that did not help either (didn't think it would). My
xbox is connected via ethernet to the router while my desktop is connected
wirelessly. This should not be a problem, as my other computer, a laptop
running windows vista ultimate as well with a wireless connection, finds the
xbox 360 just fine and vice versa. so it seems to be an issue on this pc.
the pc is newly formatted so it's not like i have a ton of junk software on
it. I am very technical with computers, but i can't figure this out, or find
the answer online for the life of me. All settings within Onecare that have
to do with Media Center or the Xbox are set to allowed. I have installed all
Vista updates to date, so this is not the issue either. What could the
problem be if my laptop that is wireless and also running vista, can connect
with no problems, yet my desktop cannot, but once was two days ago without
issue? Thanks for your help in advance.