its called overscan, and it is something your TV is doing. You may be able to turn it off in its menus (would have thought dot for dot was the option, but perhaps not) you will need to do some searches on this site and others for overscan and see if there are any solutions listed. The Aquos rings a bell for this problem. Ideally you want it to stop doing it without having to manually edit modelines. Also, the mythtv modeline database is useful..