Hi,
I used to work with Arduino 1.0.6 and upgraded to 1.6.4 (Full installation)
I had good fun with the Arduino using 1.0.6 without any issues 
Now when I plug in my old but genuine Arduino Uno it gives a message that the USB Device is not recognised.
When I go to the device manager, under Universal Serial Bus Controllers, there is an entry that says "Unknown USB Device (Device Descriptor Request Failed)
When I unplug the Uno, this entry in the register disappears.
Plugging in my Uno, the message comes up again.
I tried to unistall the device drivers, and I tried to update the device drivers. Nothing works 
I tries this as well with a chinese clone that worked perfectly previously - same result.
Please help!
Thanks
Nico