Hi, I have comcast hd cable with cable box. and for the last couple of days if I'm on a sd channel and hit the guide button to see what is on other channels and then exit out and go back to watching the same channel. the picture stays small like it was when the guide screen was on. But if i do the same thing while on an hd channel and then exit out the picture goes back to normal size????? I dont know if someone has hit a button on the remote by mistake or what but I am lost!! Help Also if it helps I live in indianapolis in and have a samsung led dlp 5687 tv

The box is malfunctioning. Try unplugging it for a minute. If it still does it, exchange it for another one.

What type of box is it?

motorola dcx3400