Gyro resetting and recalling?

[Tom Line]

We have a very odd occurrence going on with our robot.

First, I modified the gyro code that that it locks out the other routines while calibrating (just to stop over-eager folks on our team from driving in practice mode while the gyro is calibrating).

On occasion when we take a really hard hit, the gyro suddenly starts recalibrating itself and as a result the robot stops responding until the cal is complete.

Any idea why this might happen?

[Mark McLeod]

I'd certainly guess your RC is resetting.
Could be a loose Anderson connector jarred by the impact, or the motors suddenly stalling and draw max current, thereby dropping your main battery voltage.
That wouldn't be true if your backup battery is charged, though.