Hi Walter, I also keep getting a message saying "The system can't execute the navigation program". I reloaded 6.5.6 and still get it.. I unplug and reboot, and it comes up.. This has only happened since my update last week... I'll give it a try tomorrow and see how it goes...
It also seems that my connection on the board may be loose. When I plug it in to the power supply at home, any movement will force a reboot... I'll send this information from help page..
Wade Leveille