Dell Optiplex 160 was working fine then Win XP no longer recognises USB mass storage devices. All 4 USB ports give same “unknown device” message. I currently have SP3 installed. I have tried most MS and other suggested fixes to no avail, including re-installation of hardware drivers from Dell. I have tried several brands of USB thumb drives with same result. These devices work fine in a laptop that also has Win XP SP3. I am pretty knowledgeable about computers but this is completely baffling to me. I ran into some posts suggesting that SP2 may have triggered the problem.
