If the software is freezing, try a "soft reset" by turning off the ignition for 5 minutes. For a "hard reset," disconnect the car battery for about 30 minutes to clear the system's cache.
The sys.txt file is the brain of Navione. If this file is corrupted or misconfigured, the software will crash immediately on launch. A "Navione GPS software fixed" outcome often involves rewriting this file. navione gps software fixed