I have the EXACT same problem - can you tell me if you have resolved this and how
Mine is a 330D 01 with the 4:3 screen
I know that on mine, disconnecting the tv tuner seems to make it work again (could just be coincidence) even though it makes the screen go blank.
Not sure if it is some form of conflict between systems.
What part of the system contins the amp - that would be my first thought but can't find much info at all.