My Sony TV screenhas red background 24/7 but ok when watching DVD

This morning I switched on my Sony TV and the picture was washed through with a yellow tinge. Now I've switched it on again after letting it rest its got a bright red / neon vibrant red washing throughout the whole screen. The image is fine when I watch dvd's - can any one suggest source of problem. I'm in the uk and the TV signal is a cable signal through Homechoice provider down the phone line. Many thanks in advance, Nic