Samsung 46" LCD w/cable converter box connected - picture cut off

I have a 46" Samsung LCD television connected to a cable company converter box using the TV's HDMI input. The picture is cut off and you especially notice it on sports channels and programs when information displayed at the top or bottom of the screen is cut off. The "Zoom1" and "Zoom2" options are grayed out and not available in the Samsung "Picture Options" menu (this seems like a setting problem or malfunction also?). I'm just trying to find out how to truly fit the entire picture to the screen. Could it be just a Samsung LCD TV setting or a cable box setting or a combination of both? While this is not a PC related issue (just a TV that is not connected to a PC), I wanted to check this community for input. Any suggestions are greatly appreciated. Thanks and have a great day!