I have Windows XP home edition on a DELL desktop that is 6-8 years old. My computer used to run fast but as years went on it got slower and slower. I defrag often and run disc clean-ups. I use Ccleaner and lots of other stuff. When I ran DELL diagnostics it said.....Some priority items need attention. then the message " The scan failed with the following error: Passed ; ChildDeviceHasUnknownProblem" Can someone tell me what this means and how to fix it? Thank you!