delay on screen when changing channels

I have a Panny PX50U and today when I turned on the screen there was an image frozen on the screen, almost as if I had the TV on pause. I changed the channel and then it was fine....But it seems as though when I change the channels there is a delay. I hear the voice before I see the screen. Never had the problem before and was wondering what it could be.


Any help appreciated...

thanks