Have you checked the display format for your DVD player and your TV? Many TV's also can set the viewing format.
I know this is a bit off topic but;
FYI; Letterbox is a vastly superior "standard"[there is more than one, as many as 16 or so I believe but I digress] the picture quality of "letterbox" is also vastly superior to "pan and scan" formats.
You lose more than a "few inches" on the sides and top and bottom, you actually lose 46 % of the viewing area with Pan and Scan, yes Forty-Six Percent. In "letterbox" you see the entire picture as it was shot and directed, pan and scan is just that, the video has been enlarged [making it more grainy and less sharp] also as the name suggests the movie is re-directed post production; the "camera" PANS around the screen instead of just showing the entire picture, someone must decide what is to be panned and scanned and that which is not is discarded leaving you with a vastly ijnferior product, even on 4:3 television.
TCM has a fantastic explanation of "Letterbox" V. "Pan and Scan",[presented by Academy Award Directors and Producers] once you watch it you will never use Pan and Scan again.
"'You build the frame to fit the painting, right? You don't hack off part of the painting to fit some pre-existing frame.'"
"'Films are just as much works of art as paintings are, so why shouldn't the same standards apply'"
Further: This also results in what are incorrectly referred to as "black bars" at the top and bottom of the screen. In reality, these "black bars" are actually unused areas of the screen. The areas are black to allow for better contrast.
Further still: some TV's do not raster in the black contrast areas of Letterbox and use the full raster only in the "painted" or area that holds video IE the full resolution capability is "painted" in the "video" area and not "wasted" in the black contrast area.