Did you ever find out what was causing this problem? I just had Comcast installed today, and I have this same shadow across the top. I thought it was something that would go away, but it's constant.
Hello Jhera - No I never did find out about the shadow. I ended up purchasing a new TV. The second day I had it, the shadow appeared. I had my old TV ready to take to the dump, but thought I better check it. Once I se it up with my Apple TV playing Netflix, the shadow was no longer there and I realized the TV is not the issue. The new set only had the shadow appear for a day.
If I were you, I would unplug the cable box and try it with somthing like a blue ray player or apple tv so you know it's not your TV. I have no idea why it appeared on the new set or why it mysteriously disappeared.
Good luck! Perhaps the xfinity folks have an answer since it must have happened at least occasionally.
I changed some settings in the X1 box. I don't remember which ones. I do know that I chose 16:9 at 720 for resolution and Zoom on. The black shadow is gone, but now I lose the outer edges of some TV shows when using the X1's recording function. During iZombie and some commercials, I noticed that the text on the left and right sides of the screen gets cut off. That said, changing the resolution and zoom back does nothing to fix this problem and it's not an issue with my TV. I also have the widescreen option chosen for my TV, btw, so I don't know why the X1 box, given the two settings, keeps showing the non-widescreen format.
It's an older Magnavox HDTV Monitor flatscreen that doesn't have fit-to-screen. It only offers 4:3, Zoom 16:9, Superwide and Widescreen as screen formatting options.
I think this is something either with the X1 box or from Comcast's end since the cut off happens almost the same no matter which of those above formats I choose. The only difference? If I pick 16:9 on my TV, then the bottom gets cut off. With the other options, the image itself looks the same within black bars except for being either more compressed or spread out across the screen, depending on the option. I tested this with iZombie paused OnDemand. No matter which option I chose, the actual image was cut off on the left and right side making it impossible to read the comic book style text often used in that show when switching between scenes. While watching TWD tonight, part of the "A" on AMC was cut off on the left side. Some commercials lose entire words on both sides.