I have just solved the same problem with a green screen on my Panasonic TX 19LXD8 TVwhen playing a DVD.
I originally connected my DVD player to the TV with a scart lead only - resultying in a green screen.
I have now added a HDMI lead from DVD player to TV and with the necessary set-up alterations on the DVD player and set the TV to HDMI output and now the colour is fine!
Martyn
August 2009