Xbox 360 doesn't detect UMS

[Fowz]

Until last monday UMS worked fine, but then my 360 stopped recognizing my PC. Now that I fixed this error I thought everything would be normal again but it isn't.
What I did to fix the 360 doesn't finding my PC: activated the UPnP Device Host on Services.

Now I'm lost to what to do to the 360 find the UMS again on the video player.
I've looked for a solution on the forum but nothing worked for me, so anyone have anything for me to start?

[DeFlanko]

Got some logs to look at?

[squadjot]

Just to pinpoint the error, have you tried disabling your windows firewall?