Have you read of the thread 'A Really Daft Question' in the Digital TV section of this forum.
What source are you using? WS anamorphic DVD, Digital TV etc?
If the source is in WS anamorphic then the TV will switch to the correct setting. If it isn't then, chances are it will switch to the wrong one, depending on how you've got it set it up.
Some TVs use a 'smart' mode for non-ws material where they basically stretch the pic at the sides and crop the top & bottom off. Nothing smart about that if you ask me.
You're best using the 4:3 setting for non-ws material.
I can never undserstand why some people have the TV stretch the pic and distort it just to fill the screen. It's kidology, they feel they're missing out on something if they leave it in 4:3 with black borders down the sides