2002 Explorer quits on the road.

2002 Ford Explorer turns off while driving. The obvious display on the front panel is that the odometer numbers are replaced with dashes. After an unspecified length of time (1 minute, 2hours, 6 hours) the car will start again. This has happened 5 times, but after I had the car towed to a Ford dealer the car will not quit for the dealer so they will not do anything to fix it. Any suggestions as to what could be the problem?