Do you by any chance have a TV / HDPVR that shares composite video with component green? (the old style yellow one shares the same port as the Green one).
I sometimes get that problem on my samsung TV. It seems to be a hit and miss for me, I just take the cables out, inspect them, then put them back.
you need to make sure they are properly connected. If not connected properly, you will get no color, or only certain colors will show.
If anything, you could try exchanging your cables for a new set