Having troublewith a peripheral? Always check System Profiler first. If you only remember oneperipheral troubleshooting technique, it should be this: connected peripheralsappear in System Profiler regardless of functioning software drivers. In otherwords, if a connected peripheral does not show up in System Profiler, then youare almost certainly experiencing a hardware failure. If a connected peripheralappears as normal in System Profiler, you are probably experiencing a softwaredriver issue. In that case, use System Profiler to validate whether theexpected extensions are loaded.

Excerptedfrom Mac OS X SupportEssentials, Second Edition by Kevin M. White