The good news is that your issue is repeatable.
So make it happen again and collect as much data as you can about it to answer these questions...
The devices almost all have LEDs and a boot sequence. Does the cRIO reboot? Does the radio reboot? Does the camera reboot?
Look at the Charts tab of the DS. How low did the yellow voltage plot go before the disconnect?
If the radio is the only device to reboot, trace wires and verify that it is connected through the regulator and the special 12V connector on the end of the PD near the cRIO. The link below, radio section shows images.
http://wpilib.screenstepslive.com/s/...control-system
If it is just the cRIO, then verify it is connected to its special boosted location on the PD.
If these seem correct, it may be informative to measure with a multimeter to verify the regulation features are working properly.
That is enough If ... then conjecture. Let us know the results of the test.
Greg McKaskle