Device restart: causes?

HI,

I had an email from someone using one of my apps complaining of his watch restarting in the middle of a session... I was quite surprised as I've had no bug reports on that app for many, many months and I can't replicate any errors anywhere. There is nothing in ERA and a restart is not like a crash in any case.

So...

What causes a device to restart? 

Is it likely to be a problem local to him?

Has anybody else experienced this kind of report or seen it themselves?

Thanks,

Baffled of Dublin

PS: In case it matters, device (according to Garmin email) was:

  • Device Name: Descent Mk2i
  • Firmware Version: 8.40