I found this @ Microsoft: USB devices based on earlier versions of the USB specification may create ghost devices that appear when the device is connected, and then disappear when the device is disconnected. Also, the device may work just fine, but may create a disassociated unknown device, which is typically caused by either outdated or incorrectly configured firmware. In this case, contact the device manufacturer for updated firmware. A ghosted device can appear if you manually install a driver for a Plug and Play device that the computer has already detected and installed. You can resolve this issue by deleting the ghosted device. Hope this helps