PC won't allow sharing to Xbox 360

I set up my network back in April and everything was working fine until about 2 weeks ago when my network quit recognizing my Xbox 360 completely. I am using just a switch and getting internet to both Xbox and Computer. I finally have it to where my Xbox shows up on my network map, but when i go to allow it for streaming media it doesn't show up. before everything went out i hadn't done anything to my computer. Like i said i see that it is on the network, it just doesn't show up on the list of devices to allow streaming to. Any way to update that list for everything on the network? Do i have to do something to my Xbox. Any idea would be helpful i am willing to try anything

yes i have already read through that. it isn't a connectiopn issue. In the media streaming options under network and sharing center doesn't show my xbox while the network map does

i did not install or remove any software. I do have automatic updates enabled for all my software if that could have done it. I am using windows firewall, and WMP11 to stream. I am using the xbox as a media extender, but i am not using media center. As a test i tried to set up media center and they would not recognize each other still. If there is someway to manually add to that sharing list that would be what i need.

If you have any type of A/V software installed or a third party firewall you should uninstall them completely then test to see if the Xbox shows up after that.

I have no sort of a/v software but WMP11, i have tried uninstalling and re installing that. I am only running windows firewall.