Xfinity live TV stream was working perfectly for me for a while. Then it stopped working. I could get the TV Guide screen to appear, but it would hang trying to connect with the circles/dots going across the screen. I finally got it to work again and this is how. I downloaded the free version of Glary Utilities and ran it. The program corrects different problems including registries. Voila, my streaming is back!
Good Luck all.