I tried disconnecting all my USB connections to the MB USB headers, including the front panel USB 3 and USB 2 cables, plus the USB cable from the Corsair H 110i liquid cooler, which I am supposed to connect to the MB. All the USB ports look ok. I finally resolved this error by pushing the "clear CMOS" button at the back of MB.
This solution is probably the easiest one you can try before doing something to your MB.