I originally had my xbox streaming with my PC. I use Time Warner Business Class Roadrunner 10x1. I have an AMBIT U10C020 Modem/Router. It is a Cable Modem with Router built in, 4 ports. when I first got the Xbox 360, and I hooked it up it immediately found my PC and was streaming fine. I have Vista Business so I was not using Media Center, but the PC streaming was working fine for all my music and videos. I got a new entertainment center so I powered down the Xbox and PC to transfer to new entertainment center. I am very savvy to the connections of this and I reconnected it exactly as before. All fo a sudden my PC does not recognize my XBox and vice versa. Xbox tech support has been unable to help in more than a dozen attempts. I have had time warner make sure all the necessary port are open and have done so manually as well to be sure. It simply quit recognizing when I moved it. I moved the XBox 1 piece and one cable at a time to be sure it was reconnected exactly as before. By the way, Xbox live works fine, my PC internet works fine and there is only a router/modem connected, nothing else. Whay is this? Yhank you
P.S. the fire wall is the windows firewall and I use Live One Care paid version, not trial or free, and I have already tried disabling.
I assume you are running WMP 10/11/12. If the 360 is not showing up in the connections/sharing tab in WMP you may need to get/reinstall media center connect, possible like other MS programs it just lost it's settings.