I have tried changing various things but get the same message every time. The error message is very non-specific - it does not say which driver is actually missing. This could be a DVD, USB or Hard disk driver. 'A media driver your computer needs is missing.

The Windows 8.1 installer hangs very early on with the complaint I attached the host physical DVD drive to the VM, inserted the 64bit installer DVD and started the VM. In VirtualBox, I created a new VM, selecting the type 'Microsoft Windows', Version Windows 8.1 (64 bit). My physical CPU is a i7 4770k with 8G of RAM, OS installed on SSD. My VirtualBox version is 4.3.6 r91406, running on UbuntuStudio 13.10 64 bit version(has XFCE desktop - otherwise pretty much the same as Ubuntu 13.10). I have this problem when trying to install Windows 8.1 Pro 64 bit edition from the installation DVD that came with the boxed Windows 8.1 Pro full installation set. I also found a work-around, though it requires you to have a Windows 8.1 product key. Since I have this same issue I will try to provide the additional information necessary to figure out what is going on.

Virtualbox download for windows 8.1