No picture only sound/audio on HD channels?

Why are there gray bars on top and bottom of picture on HD channels?

• We just got a brand new 55" TV. When watching the HD channels there are gray bars along the top and bottom of the picture. I tried googling this and I can not figure out why this is or if there is a setting we are missing or something. I was under the impression that the HD channels would fill the whole screen because the TV is supposed to be 16:9 aspect. We also watched a movie last night and there were black bars on the top and the bottom that were actually pretty large and it seemed like we were not seeing the entire picture at some points (like peoples heads were cut off) So confused, please help!

• Answer:

  The channels are not set to your tv. You have to manually change the picture aspect ratio. Look at your remote for a picture-in-picture button or look for something that changes the the screen size. There is a button, if you don't find one, keep looking.