Windows Media player no longer streaming

Hi,
I had windows media player set up to be able to stream content(e.g. videos, music, picture etc) from my PC to my T-box.

I havnt use this feature in a while and I went to use it last night but my tbox can not pick up my PC.

When I go to windows media setting I go:
Stream > Turn on media streaming > Then I get a pop up saying turn it on, with UAC logo next to it.

I am admin on it so it should work. I click on it nothing happens...
How can I get media player to stream again or how do I reset media player to default setting so I can set it up again

So I have done a couple of System restore, and they have helped me narrow it down to a windows update....
but I have no idea which one... How can I tell which one is causing this problem