i just face the same problem.. and this might be solution.
i use macbook pro late 2011 and install windows 8.1.
(prepare your USB min. 4GB)
- ensure you download the windows support software from apple bootcamp.
- you will get windows support folder in the usb.
- restart to windows
- open your usb file there..
- you will find setup.exe
- right click on your setup.exe
- go to compability tab
- check the box of Run this program in compability mode for (and change the list to windows 8)
- apply
- right click again on setup.exe
- run as administrator
- and click. run the program without getting help.
- installing
- restart
- and voilaaa... all works