You will need a new keyboard if you have already tried new ports. The bus controller in the keyboard saying what it is what it does died which is common but not. However really hard to ever fix without a little knowlage on programming and wiring.My keyboard stopped randomly and when I went to go unplug it and plug it back in it said Unknow USB Device
That's what I said.... If that hasn't worked it' the controller on the board. "Try new ports" other wise the controller is deadDid you try all the USB ports?