My Panasonic Viera TH-50px50u loses its blue color after i play a dvd. How do i fix it?

There exists an issue between the TV itself and my dvd player (a Denon DVD-1710). When playing a DVD through the fore mentioned device the color blue becomes more blue-green. This issue has been fixed by a repair man, and yet here I am again. How can I fix this issue, or at least figure out where the problem lies.