> Moral of the story: even insane-looking problems are sometimes real. To me the moral of the story (and my experience) is: user's problems are usually real, but don't trust their ability to diagnose the actual cause.
I used to do some help desk as part of my dev job, and from my experience, users easily assign any random fact as the source of the problem. Often things like "correlation is causation" or *post hoc ergo propter hoc" (after that, therefore because of that). Good as heuristics, but bad when they are substitutes for reasoning.
Users cannot diagnose at all because they have no idea of how the thing they are using works (which often normal - we are the engineers, they are the users) (in this regard, users that think they know "that stuff" are among the most difficult to deal with). One cannot properly diagnose something one doesn't understand well.