Linux – VirtualBox stuck on Windows Logo

What version of .Net does the computer you're trying to run this on have installed? If possible, I would installed the latest versions

Basically, what this error is telling you is that the program requested a class from the registry, which makes me think there's something that is not installed on the computer that's required to run Virtual Box Portable.

Did you ever get to the "Portable-VirtualBox *** Extract and/or Compress ***" window?

Edit:

Okay, next thought - it looks like you're running Windows 7. Do you have UAC disabled? VirtualBox is probably trying to register a COM object with the OS, and without administrative permissions, it won't be able to. I would try running the portable exe as an administrator (right-click -> Run as administrator) or, if it's disabled, enabling UAC and see if that helps.

Finally found the answer. It all hinges on Hyper-V and the fact that it's enabled by default in Windows 8.1 Pro (as well as in other Pro and server Windows versions). With Hyper-V running, other hypervisors (like VirtualBox, VMWare and Android emulator) are crippled.

You could, potentially, disable Hyper-V from the Windows Add/Remove Features dialog. But what if you use Hyper-V for development or testing (i.e. WP8 development)?

The solution is to boot Windows with Hyper-V turned off. And the easiest way to do it, is to create a new boot configuration, with Hyper-V off, and boot to it whenever you need to use VirtualBox.

There are several step-by-step guides on how to create a new boot configuration - this one has some screen shots.