Lost use of mass storage device

I have a computer that has W2K w service pack 4. A few weeks ago I lost the ability to read any mass storage device. The USB ports are still active and can read other USB devices. I have been researching this issue and cannot find an answer. I have tried to uninstall the and reinstall anything that deals with the USB ports, no luck. I have tried to reinstall the drivers for the mass storage devices, no luck. The storage devices work on other computers but not this one. What is the corrective action?