We get that question a lot in our electronic service department. First and foremost, nothing is wrong with your TV set. The real reason why you see bars on the left and right side of your new HDTV has to do with picture size.
Originally TV sets were round and it would have been difficult to show a wide screen format on them. The 4:3 format was adopted to fit the round screen of old TVs. That worked just fine for decades, until technology progressed. Along comes HDTV and in addition to greatly improving the picture, they decided to make it 16:9 widescreen as well to emulate the movie experience. Obviously, if you take a 4:3 SD picture and try to show it on a 16:9 widescreen, it will not fit. Enter pillar boxes, or vertical bars on the left and right of the screen. It may seem obnoxious to look at left and right bars when watching an older program on an HDTV, but it beats the alternative of having to stretch the entire image, making everything look awkward.