As per our comments, try the keyboard in the BIOS to prove if it is a driver issue or not. Since it works in the BIOS, we can return to the drives for Windows.
In device manager, expand "Universal Serial Bus controllers", right click on the "Host Controller" and Uninstall.
Failing that, the driver can be downloaded here http://drivers.softpedia.com/dyn-postdownload.php?p=43160&t=0&i=1 . When downloaded, open Device manager, find the USB keyboard (with the yellow exclamation mark), right click, properties. Open 2nd tab called Driver, and click Update driver. Then, click on Browse my computer for driver software.
Click browse and select the new .dll file.