I'll respond to let audiomixer know that we are reading the thread, just don't have any solutions.
It did occur to me that one possibility is that different inputs on the TV might cause different behavior. Is your friend using different inputs for the different sources, or one input switched through a receiver or similar?
Component video cables used for BD player (for BD and DVD) - but what is used for the cable box? Also component? Is it an HD box, or just SD? Or is the cable hooked up to the TV directly via RF coax?
It is possible if a receiver is being used for all sources that the receiver is doing something weird to the different inputs.
More info on how the different sources are connected, please...
shinksma