Xbox 360 Extenders can't connect until Win8 PC is rebooted

[AdamUCF]

I've been using a Win7 MCPC for years with Xbox 360 as an extender and it's been working ok but the Win7 PC is getting a bit long in the tooth so I moved my InfiniTV to my Win8 closet PC/server and bought another Xbox 360 to replace the one MCPC. But now I'm running into a really frustrating issue with my Xbox 360s. Basically the Xbox 360 can only connect to the MCPC once until the PC before the PC needs to be rebooted in order to allow the Xbox to connect again. Here's the steps...

1. PC and Xboxes are started. Launch MC on Xbox 360 and it connects fine to Win8 Media Center.
2. Turn off Xbox 360
3. Turn on Xbox 360 and launch MC. It will say PC not found. Restarting Xbox again does nothing to fix.
4. Restart PC and Xbox 360 can connect fine again

The only things I've been able to find in the system logs is that when there's a successful connection, I get 2 event entries in the Media Center log... The first is "Media Center Extender software was sent to Extender 'uuid:..." and then followed by "The Media Center Extender session was established." a few seconds later. When the connection fails I get the first message but not the second.

Any ideas? I've got all the latest NIC drivers, etc. Tried restarting various Media Center services but only a reboot seems to fix it. Obviously rebooting my PC manually every time I want to turn on an extender is a terrible workaround.