Media Center Seems to Kill Internet Connection

I was setting up Windows Media Center with my Xbox 360 so I could stream movies to my TV from my PC. After overcoming my usual issues getting the Xbox to find the PC and vice versa, I finally got it set up, or so I thought. At some point during the connection process, what I am assuming is the media center network sharing process, messes with the internet connection of my PC, perhaps taking priority over the internet connection itself.

What happens:
1)I open media center on my computer, check everything is set up correctly.
2)The Xbox finds and connects to the PC, then opens media center, leading me to the menu.
3)When I look in my media libraries for my movies, nothing shows up, it says it cant find any libraries.
4)I go back to my PC, Windows' network manager says I'm still connected just fine, but applications like Skype, Steam, and my web browsers, are unable to connect to web servers, peers, etc.
5)I restart media center on the Xbox, and it's now unable to connect to my PC either.

So at some point when it establishes the connection, it kills the network on my PC, so it cant connect to anything, including LAN devices and web servers, but Windows still thinks its connected. When I try to diagnose the issue with Windows, it believes there is something wrong with my modem, though other systems in the house can still connect to it fine. To try resolve the issue I close WMC, and kill any processes I am able to see which are connected to it, e.g. the windows media center networking process, or whatever its called (Its something like that), but this still does nothing, and I have to restart the system to get my internet connection back.

Has anyone had a similar issue, or does anyone know of any possible solutions to the issue?

Thanks,
Tom

Thanks, I'll give it a go.