I remember I had a problem with my tv once with the output in b&w, It turned out to be the wrong thing selected (PAL, NTSC 3.4, NTSC 2.4) Not quite sure what the numbers were, but there were two different NTSC number, and it was on the wrong one. I know NTSC is what we use in the staes, and PAL is for Europe. Probably won't help, but that was my issue, worth checking I guess.
+1. This is actually a very good observation and is possibly the problem. I must be getting old, I forgot all about that. I shouldn't have as I used to have a multi-format TV I bought in Germany a million years ago that had to be reconfigured for NTSC when I brought it back to the States.