I'd have to pull the exact part numbers but I have the floor mounted DVD unit (#4 below), with wireless headphones and headrest monitors. Took it in to dealer and they say "a diagnosis revealed a burnt out module within the DVD unit" is the culprit for the system playing in b&w. They suggested replacing the DVD unit.

I read through the system manual to troubleshoot and it made mention of the monitors playing in b&w if it runs for an extended period and gets too hot. The longest it's ever been used is the length of a feature film