It’s the former. It just shuts off and then I restart it. Occasionally, rarely but sometimes, I get signed out of my user account and then back in. That’s an odd reaction as it always terrifies me that my computer is crashing, but it isn’t.
I’m using a MBP. Any more info on that as a hardware problem? I have another 4 months as a warranty and if there really is a problem, I’d love to try and get the apple store to somehow help me. The fact you said they dont admit it doesn’t augur well.