I have been having the issue of my battery draining on my 2005 x5 4.8is, I replaced the battery saturday and started to check a few thing out, 1 of the first things I noticed when i was working on it was the dvd part of the sat/nav in the back compartment never shut down. So i closed everything thing up and let the car go to sleep and still the light was still on. So i have been reading up on the MKiv units and it sounds like there a little fragile. So what is the best route to take with this ? replace the dvd in the rear compartment ? replace the head unit up front ? I had notice in the summer that the screen at time was all messed up with a dim screen, then discolored. I have also read a few people using a navcoder, if the battery had died do these need to be reprogrammed ?