Hi James, It's very random, but usually not when it has gone into deep sleep, can be maybe after half an hour, I've been trying to work out what I maybe doing, I don't change Atty's or tanks very often, yesterday it did it twice, after the second time I removed the batteries and replaced, hasn't done it since, morning here in Australia and I just woke it up this morning, no problem, White screen with red letters when it happens - Cheers Bill