2001 Prius stalled when I put it in gear

Ladies and Gentlemen:

I have a 2001 Prius w/150K miles on it. Today I was leaving a parking lot (it had been idling in park) and it stalled when I put it in Drive. I tried it a few times and it stalled (it also did it when I tried to go into Reverse). Anyway, after waiting a few minutes, it worked again.

By the way, I have plenty of gas in the tank.

Any help would be greatly appreciated!!

Any guidance would be appreciated.