2001 Ford Taurus 2001 Taurus

I have a 2001 Ford Taurus. For the past few days the Check Engine Light was on, although the car continued to run fine. This morning while pulling away from a parking spot the car shut down. When I tried to restart the car it would not crank and there was no power to any of the cars electrical componets. After sitting a few few minutes I attempted to restart the car. The car started and the Check Engine light was no longer on. I took the car to my mechanic but he said he could not test for the trouble code while the light was not lit. He did check the charging system and said everything was fine. I returned home and after the car sat for a while a I once again tried to start it. This time the electrical system was shut down again as before, and the Check Engine light was still not lit up. Another attempt later and the car started fine and still no return of the check engine light. Any suggestions?