iI just facefaced the same problem.. and this might be the solution.
iI use macbook proMacBook Pro late 2011 and install windowsinstalled Windows 8.1.
(prepare your USB min. 4GB)
- ensure you download the windowsWindows support software from apple bootcampApple Bootcamp.
- you will get windowsWindows support folder in the usbUSB.
- restart to windowsWindows
- open your usbUSB 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 windowsWindows 8)
- apply
- right click again on setup.exe
- run as administrator
- and click. run the program without getting help.
- installing
- restart
- and voilaaavoila... alleverything works.