Most well written software has what is called a hook routine where if the processor encounters? corrupted data it jumps to a safe start point rather than lockup with no way out. I suspect in the case of the 857 it is the non volatile part of the software where it will reload the factory default.
The volatile part part of software can be corrupted by RF getting into the radio, common mode currents etc. Doing a reset is a good thing although it's annoying but warns you there is possibly an external problem.
ZL4IV