Difficult people appear in every company, regardless of the specific industry. Some industries seem to breed more than others but anyone contemplating a computer career should be prepared to deal with a variety of people, some of which might not be the most pleasant.
Most users are nice people who are honestly having trouble with their computers.
You can help them quickly and move onto the next. As the name suggest this type of computer user, generally a computerphobe at heart, calls again and again, with close to the same question. Then, when the support person calls or arrives at the office, the user doesn't want to learn how to do the task. They want the support person to do it for them. Often this is done in the guise of critical deadline work but after several calls it becomes clear that the user has larger problems.