Help! Error 538 for Xbox 360 extender setup

[bengalbhai]

Hi community - any help you can offer would be greatly appreciated - have tried and read most of the community discussions out there, but still stuck!

I got an Xbox 360 for cheap this Christmas, and thought I would finally try to set up an Extender from my HTPC. I'm running a Dell Zino HTPC with Windows 7 Professional 64-bit. It's connected via two Zyxel 500 Mbps Powerline adapters to my Xbox (my WiFi and Cable Modem communicate via the Zyxel switch). My Network map from the HTPC shows this setup, and recognizes the Xbox. The Xbox internet connection appears to be working fine; when I try to find computers from the Xbox however, I can see my laptop easily via wireless, and if I wait for minutes, my HTPC eventually shows, but I cannot connect to it.

When I tried to add the Extender from the HTPC, it gets through just the first checkbox of "Configure computer settings" before eventually timing out. The Event viewer gives me "Error 538: Media Center Extender Setup failed as the Extender was detected on the network but the UPnP search for the Extender failed (timed out after 20000ms)."

Things I've tried:
- Updated my Ethernet adapter drivers.
- I'm just running Windows Firewall (which I've tried taking down, same error).
- I tried restarting the UPnP service (no benefit).
- The Internet Connection Sharing was already off.
- Deleted the Certificate via MMC.
- The Media Center Extender service was disabled, so I enabled it and tried again, no benefit, and then it was disabled all by itself again ----- could this be the error?
- I have a Rosewill wireless router, and Multicast and UPnP are turned on there (but I'm not even using the wireless router in this connection; my laptop (also running Windows 7 is able to add the Xbox as an Extender anyway; yes, I already uninstalled it as an Extender before trying again).
- Do my Zyxel powerline adapters need to be configured somehow? I haven't ready of anyone having a problem with them, and can't figure out what to setup on them anyway...
- I went to a system restore point before I started trying any of this, and I still get the same error message...

Any help you guys can offer would be greatly appreciated! Happy and safe New Years' Eve....

[dotbatman]

On your media center, navigate to Control Panel\All Control Panel Items\Network and Sharing Center. Make sure that the network it says you are connected to is identified as a home network. If not, click on it and change it to be one.