My two kids chipped in last xmas and gave us a Blu-ray player. With Blu-ray movies the picture is incredible. But, i am finding my old TOS, TNG, Voy and DS9 dvds look funny. The picture is somewhat stretched. We think it could be a setting we have to adjust. Onlyl the husband and i are pretty much idiots when it comes to this sort of thing, so we've been suffering through with the stretched pictures.
It is a setting, either in your player or in your TV. In the setup menu of your player, make sure you select "Normal" rather than "Full" (the most common names for the settings). That should solve your problem. If not, send me a pm with the TV and player model numbers and makes and I'll see what I can find out for you (A/V is something of a hobby of mine--I belong to one Trek board, but 8 A/V boards).