[BradAMiller]

Definitely turn off the motor safety on the RobotDrive object, not the individual motor controllers and see if that fixes the problem. In the library, RobotDrive is the only place where the motor safety stuff is enabled by default, and as Omar said, it is part of the RobotDrive class as a whole. The thought was that it would stopping the runaway program from driving on it's own was the highest priority.

Use something like:
drive.SetSafetyEnabled(false);

Please let us know if does it for you.