I could get WMC to setup fine,but not connect to my PC. I could connect to Xbox Live just fine, but it could not find my Stupid Windows machine sitting right next to it.
Here's what I did to get it to work (AT LAST!!!)
(Including trying EVERYTHING so far in this thread, this worked the trick for me)
NOTE: I had to do BOTH of these steps. It appears
both of these conditions must be met. I could not get it to work by doing just one or the other. Your mileage may vary.
1)-->TURN OFF INTERNET CONNECTION SHARING (If you had your PC set up to use XBMC with your Xbox, you may have had this option turned on. I
hadto turn this off to get WMC to connect. Not 100% clear as to why, but it worked for me.
2)-->Enter the MAC address of the Xbox360 itself into the Alternate MAC Address setting under Additional Settings/Advanced Settings on your Xbox360. I used the Wired MAC Address of the Xbox360. (What it says on the lower left of the advanced settings page) Also check to be sure this MAC address matches the one under the properties for your Allowed Xbox360 in WMC.
Think of it like this- WMC is like one of those drivers at the airport holding up a sign with their client's name on it. XBox360 arrives at the airport with her assistant. The assistant spots the driver. "OK, we're here. Let's go." she says to him. The driver says, "Wait, who are you?" The assistant takes him literally and shows him her passport, with HER name on it, not XBox360's. "Sorry," says the driver, "you're not my customer".
Now, the assistant is flustered until suddenly she gets a call from The Office who tells her to use Xbox360's passport, not her own. The driver needs to see Xbox360's credentials. The assistant takes XBox360's passport and shows it to the driver, and off they go.
(BTW, I'm using my original Xbox wireless adapter (model MN-740) with the cable that came with my Xbox360. If you can get to Live, your cable's fine. Haven't heard from any of these posters if they are using the new Xbox360 USB wireless adapter or their old one, like me.
HTH