I have noticed that some DVD players, Pre/Processors and TV's do have a setting where you can play the source in black and white. Check your settings.
Although my guess would be that your component cables are mixed up. Make sure Y=Y Pb/Cb=Pb/Cb PR/Cr=PR/Cr
Although my guess would be that your component cables are mixed up. Make sure Y=Y Pb/Cb=Pb/Cb PR/Cr=PR/Cr