Our local PBS stations did the same thing before switching to full-time
HD recently, Larry. There's really not anything you can do -- or, for that matter, that THEY can do -- if that's how the program comes to them from the network or PBS.
That said, I was able to minimize the problem by using the fullscreen mode on my Magnavox converter boxes. If you do this with a widescreen program, this will make people look abnormally tall, but in a case such as what you're describing, it should help.