Stepper Driver shuts down my RAMPS board...

I am building my first Prusa Mendel, with RAMPS 1.4. I have Pololu stepper drivers.

When I attach one of my drivers to the board it causes the board to shut down. This happens no matter which position I attach the driver to (X, Y, Z, or E).

I can attach the USB cable to my PC and the RAMPS responds normally without the driver attached. As soon as I attach the driver to the board the LED lights on the board go out and I can no longer connect to the board.

Has anyone else had this problem? Can the driver be saved, or should I just order a new one?

Thanks,
Steve