Hopefully this is not a difficult problem but my navigation system has been working fine until a few days ago. When entering the address to navigate to, the button lights up but then goes out and nothing happens. In the past, a screen would open with a text field for entering the address info. Also, there is a box that would have a small map in it but it's blank as well. I took the DVD out of the Nav head and cleaned it and put it back in but no change. I read thru some of the old posts looking for clues and I guess the next step would be to disconnect the battery and let it reboot? If the same thing happens is it time to go to the dealer or is ther something else I can try?