Driver for Arduino Uno

I have a XP PC that I've compiled and downloaded lots of programs on a Uno and a Micro. I can download OK, but now when I try to switch from the Micro back to the Uno, XP can't load the Uno driver. I've tried lots of combinations of restarting the IDE, restarting the computer, unplugging an replugging the USB, etc. Every time I try the micro it works, every time I try the Uno it fails. In the XP device manager, it shows the Uno but with error status. It used to be difficult to switch from the Uno to the Micro, I'd have to unplug/restart/replug etc. several times, but now the micro works every time and the Uno won't work at all.

Is the UNO an original Arduino/Genuino, or is it a clone?