If you have problems using Apple Wireless Keyboard under Windows 8, this solution might help you fix it. The problem is related to the Chinese version of the driver that the latest Windows update installs, that stops the keyboard from working.
Try the steps below:
“This finally fixed it for me: Device Manager – Open System Devices, you will find a Bluetooth HID Device. Double Click it, open Driver tab and click “Update Driver” Select Browse my Computer, then “Let me Pick”. It should now show TWO compatible drivers with exactly the same name. One of them is the Microsoft one, one is the non-working Chinese ****. Install one of them and see if the driver properties changed to the right (Microsoft) driver. If not, try again with the other one. For me, the Microsoft driver was the first one in the list, but this may be different for you. Wow, an annoying and intense hour of trouble shooting finally over…”