First, press the "Reset" button or push the stylus into the "Reset" hole, to see if the navigation software can load successfully. If the program still does not load, then the software may be corrupted. Also, if the internal memory fails to read or write and the software cannot load properly, it may be caused by hardware failure. In either case, please return the unit for exchange or repair to the retail location from which you purchased it, or contact us for further assistance.