A few years back I ran into a similar issue with a TV I had with a modded Xbox. I learned that the TV Would not show color with one NTSC format, forgot which one, either NTSC-M, or NTSC-J. However, my other TV accepted the color fine. Luckily, the XBOX was modded so I was able to flash a new output format and was able to get color on the other TV.
Which leads me back to my original point...HELP!!! Anybody have any suggestions?