Hi, I have an E39 M5 fitted with the OBC/Sat nav unit such as the one in the photo below. The problem is that I can't access the menu very easily. When I press the menu button, nothing usually happens. On the odd occasion that it does let me access the menu, the knob to the right of the screen seems very sensitive, and as soon as I touch it, it selects one of the options. I then find it very difficult to get back out that option. The radio still works but I can only operate it by using the steering wheel controls. The other buttons on the unit don't have any effect. Does anyone have any ideas?? Thanks.