Hysterical over-reaction by experts to the challenges of the Year 2000 computer problems has become one of the most tiresome features of life in the late 20th century. The prospect of global environmental and health disaster have been associated with a variety of phenomena that have proved less significant than predicted by experts. Sometimes the crises are imaginary from the start. Most of them are spread by self-styled experts. They have confronted governments and the public with evidence that cannot be adequately evaluated by anyone without specialized knowledge.