Are you feeding the SD TV with a HD Directv receiver? If so, make sure the HD receiver is set for 4:3 aspect ratio and letter box format. The receiver will also need to be set for 480i output obviously.
If you're feeding the TV with a SD receiver then I'd suggest you check some of the "cable only" channels and see if that distortion is present there. Some local stations are broadcasting a altered SD signal.
If they are connected via Coax or Composite (Red, White, Yellow), changing the aspect ratio will not make any effect. Now if the tv has a Zoom type feature, it could be just human error, or it could just be that the tv is on its last leg and ready to go to its grave finally.
Now of course it could also be that the channel they are tuning into, is using Active Format Description, that could also be causing the tv to not know what to do, and is thus cutting part of the picture off.
Really would need the model of the tv, and how the box is connected to the tv, to go any further with this.