Windows 8: "Uninstall the USB 3.0 eXtensible Host Controller Driver" alert when upgrading from Windows 7
Additional Information
Uninstalling this driver will not disable the keyboard and trackpad on a MacBook, MacBook Air, or MacBook Pro. However, external USB devices cannot be used if the driver is Uninstalled.
If you already clicked Uninstall and your external keyboard, mouse, or trackpad is inoperative in Windows 8, you'll have to delete your Windows partiton using the Boot Camp Assistant, and start over. If you are doing an upgrade install, you will have to install Windows 7, install the Boot Camp Support Software, then upgrade to Windows 8. For more information on Windows 8 installation, see the Boot Camp Installation & Setup Guide.