Update: This also seems to solve issues with people using PS3 Media Server and running into DLNA 7531 errors while streaming. Cheers!A - Yeah, this one's an annoying one. Microsoft for some reason or another thought it'd be smart to hide Windows Media Player media sharing options into the Network Settings panel. Why? Who knows.
Here's how to disable it:
1) Go to Network and Sharing Center (found by clicking your wireless/Ethernet icon in your taskbar)
2) Select Homegroup and Sharing Options
3) Select Choose Media Streaming Options
4) Click Block All
5) That's it
Now your libraries should be clean and consistent without having to deal with WMP 12's annoying integrated features. Enjoy the cleaner network architecture!