[Al Skierkiewicz]

John,
While AA batteries are capable of supplying some high currents, it is not without some other problems. By using two battery packs you do not draw down the board power below the critical 5 volts at which point the electronics cease to function. You do not specify how many servos you are using , but you need to keep in mind that even servos are in stall when they aren't moving (starting). Try going to a C cell pack and I think you will have better luck. You can use a smaller pack for the board power, like AAA or some lithium cells since it is max 10 ma and stay with the AA pack for servos if that works. You are likely getting position errors, since the micro thinks it sent commands but the servo hasn't moved.