What reasons are there that require a unit to be reset?

Apart from a power outage has anyone other suggestions that I can give my client.

The unit has only recently (three months) been fitted and has been reset three times.

It's installed in a property that is used as a holiday villa but the power is always left on. The area is usually stable for power supplies.

The fix is simple but my client is getting a little uneasy as the unit is so new.

I've double checked all the wiring and it seems fine.