Check your event log from the match and see what happened:
http://wpilib.screenstepslive.com/s/...og-file-viewer
We had a similar problem once, it was due to binding in the drive train and when the driver moved the joystick forward and reverse rapidly enough, the current draw on drive motors caused a drop in voltage significant enough to cause the crio to reboot. The event log will show if voltage drops are causing this.