My son and I built the Square Bot with careful attention to the instructions. Our problem is that, while the bot does move, one motor moves in a start and stop fashion, while the other moves in a continuous motion. Could we have accidentally caused this when we were trying to set up the controller?
You may have a VEX Servo installed instead of a VEX Motor. Check the silkscreen markings on the back of the unit and verify you are using VEX Motors and not VEX Servos. You only get 3 Motors and 1 Servo in the Starter Kit.