Having the same problem, my media sharing suddenly turned off. Watched a movie yesterday afternoon, and with nothing on that night, figured I'd watch another one. Did absolutely nothing to the PC in between, but it worked in the aft and suddenly wasn't working
hours later.
So.
Windows 7:
Have tried the clean boot method. Media streaming still won't turn on. Click button, machine thinks about it, says 'nahh', button returns to normal state, media streaming is not enabled.
Un-installed and re-installed both WMP and WMC through the windows feature. Once I had re-installed, I was able to turn media sharing on. Alas, it didn't seem to take. As now the button won't turn on, and my xbox still can't see my PC. And my button went
back to permanently non-enabled about 60 seconds later when I hit it again.
Have enabled all WMP and WMC in/out features on Windows Firewall.
I'm out of ideas. I know my network is fine, and I can stream stuff to the xbox just fine using a 3rd party program like TVersity. It works. No clue why WMP suddenly decided to stop working, but I'm not too happy about it.
Any other suggestions out there?
Edit: forgot to mention, but the WMP sharing service seems to he starting then stopping automatically. Erm, not stopping, but waiting?
UPNP and SSDP are both up and running...when I hit start on the WMP sharing service, here's the popup I get:
"The WMP Network Sharing Service on Local Computer started and then stopped. Some services stop automatically if they are not in use by other services or programs."
That doesn't seem normal to me. Once it starts, it should...stay started. Heh.