My concern is of course, that even if it works now for a while, how long before it decides to act up again? Intermittent and different sorts of faults are the worst kind of problem. I would prefer that it simply failed entirely. I suspect that if I take it back to the dealer, they will “test” it, declare nothing wrong, and want me to take it back. Buy it is certainly not user error.
Thinking about this while I watched TV (after putting it into standby mode), I got to thinking that this is perhaps not so much like a firmware problem as I had first suspected. Perhaps it is more likely to be a hardware issue. I live in Canada and we are having quite hot weather at the moment, about 32C with high humidity. Of course, I don’t have that in the house, but I do allow the indoors temperature to rise to say 24C to avoid the a/c being on all the time. I noticed before that the Atom is quite warm to the touch in these conditions, but much cooler in the morning when I get up after having the temperature much lower for sleeping.
Maybe, Naim stuff only works in a cold climate! 
Just speculations on my part.