navigator problem, the menu button not working
 

Hello all,
I have a 2005 X5 4.4 and there seems to be a problem with my navigator. the navigation and map system works with regards to inputting addresses and destination but the menu button does not work at all, so I can't change the clock or do anything and I have no control over turning the system on or off. It is on all the time and I can't turn it off. sometimes the screen back light comes and goes or fades out. I am really frustrated:confused: and don't know what the problem is and need help.