Panasonic DVD player shows EXT-L in its display.

You have switched machine onto external link mode
Either press external link on remote or find it under the flap.
Has a small child been playing with the remote?

I have the same problem. I switched off the EXT-L button (which had engaged itself spontaneously) but I cannot get the channels to change, nor tv guide nor function menus to engage. I can sometimes short cut this by pressing play which allows me into the system and gives me access to the tuner and other controls, but not always. Help!!!!