unit is stuck on USB screen, I cannot reset the unit by turning it off or using the reset switch on the bottom of the unit. I have also let the battery run flat, but on charge it still has the blue screen stating USB, also when it is hooked up to the computer I cannot find the USB it is hooked up to, so I cannot use the computer to reset or disconect. Please help I need my navman. email: v_linehan@hotmail.com