I've had pretty much every model with no problems apart from the last one. I think it's overheating, but I'm not sure. It just freezes. That's with aftermarket heatsinks too. I don't want to put a fan on it because it's in the bedroom ( and the fact I'd have to spend money on a new case, which might not fix the problem ).
Same software as on my (perfectly reliable) Pi2 in another room.