Are the component cables securely plugged in? (Assuming you have the RGB cables, of course). If that's the not the cause, you might check to see if it happens on all inputs. If it does, you might call 800-SAMSUNG to see if you can get your unit inspected and serviced.
I have a Samsung 40' Series 5 TV and the color green will not show up anymore. Grass looks brown and the picture is no good. The Red/Green contrast I tried fooling with but that didn't do anything. I have had the TV for ten months with no problems until today. Any ideas?