streaming XBMC on xbox360 issue

I have tried searching the forums but have not found an answer.
On my xbox i load Windows media center then i select xbmc option from the menu, the screen goes black and around 15 seconds later i get a connection failure error on the screen.
Does anyone know what this might be and how to fix it?

streaming from computer with win & ultimate, i have media streaming and everything else enabled on my PC

I am using version 11 eden xbmc and do not have firewall enables