We not only had to change the TV like you noted but the video source as well. Strange effect but it was spotted once before.
Be sure to call this maker for support.
I have a 37" Panasonic Viera (TC-L37U3) and there is a problem with the 4:3 aspect ratio. When I switch to this ratio setting, my TV doesn't actually squeeze the picture into a 4:3 ratio. Instead, it places two vertical black bars over the full picture on the left and right sides. It's as if it's creating a pseudo 4:3 ratio from a 16:9 picture. Quite strange. I've never seen anything like this before.
Here's a picture I made to illustrate the problem:
Does anyone have an idea as to how I could correct this and obtain a true 4:3 ratio?