Hi,
seems more to be a DVD player problem.
It seems like she have a PAL M/NTSC 3.58 Player, not a simple NTSC player.
So the disc is detected as PAL and setted to PAL M 60 Hz.
I suppose that her TV set can't handle anything else than NTSC, and that NTSC and PAL use the same négative monochrome carry signal, she can see it on B&W.
This is similar to what happen with PAL "modded" PSx1 in composite mode.. the RGB cable was the solution (it brings ARCARDE @T HOME Vidéo quality ;-) )