When I saw toe cramps I immediately thought that you might have the cleats on your shoes attached too far forward, so that you pedal too much on your toes. Don't know why they'd come when you push off from the ground, maybe they're tired and cramp under a sudden pressure, but you might want to try moving your cleats back a bit.

(I only know spd cleats btw, not road, but I'm guessing they can be adjusted a bit too)