Computers are useful, but they also can problems. one kind of problem is with the computer memory. It is not perfect, so sometimes computers lose important information. Another problem is the machinery. Computers are machines, and machines can break down. When computers break down, they may erase information, like chalk on a blackboard, or they may stop doing anything at all. There is one other, different kind of problem with computers. Some doctors say they may be bad for your health. They say you should not work with computers all day.