Is the keyboard working (moving the BIOS jumper) on the BIOS screen?
Do you know if there is any driver that needs to be install on the keyboard?
Try a BIOS recovery:
1) Turn the system off
2) Remove all the peripherals (keyboard, mouse and cd, DVD drive)
3) Remove the BIOS jumper from the board
4) Load the MW0086P.BIO file in an empty flash drive hopefully no bigger than 2g and connect it to the back panel of your board
5) Turn the system on and wait for 10 minutes until you see the BIOS update screen.
6) Then boot to the BIOS and check the latest BIOS version was loaded correctly.
You can get the latest BIOS version for the following link:
Try other USB keyboard to wipe out the old Windows server from the HD then for latest drivers for the board and keyboard . If the latest BIOS has been loaded and correctly installed on the board and the problem continues, we might be facing and incompatibility between the BIOS chip functions and the USB keyboard.