The very first part of troubleshooting is identifying the problem. That's not always easy even for skilled professionals. It's definitely not easy for the typical computer user, so when you get the call, what you are told may not match reality. This isn't to imply that users are stupid, or ignorant, or careless (though some are all of those things), but simply that they may misinterpret symptoms and miss seeing the real problem.
Professionals do the same thing. In my career I've had more than one telephone call where someone describes themselves as a competent Windows administrator but apologizes for not "knowing Unix". Sometimes we end up having an easy conversation where the problem really is simply that they need a little (sometimes a very little) Unix guidance to help them fix their issue. Sometimes it's a little more involved: they've hit a tough nut and they'd really have needed years of experience to have any hope of fixing things.
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