I get the following error (and yes I know this has been reported many times, but please read further): VT-x/AMD-V hardware acceleration is not available on your system. Your 64-bit guest will fail to detect a 64-bit CPU and will not be able to boot.
The issue is that Virtualisation is enabled in my BIOS and I also made sure my BIOS is upgraded to the latest version.
Here is the thing: I used VirtualBox on the same machine, but with Windows 7 and I could run exactly the same x64 guest images.
Best Answer
All what you need is disabling Hyper-V. Run command prompt with administrator rights and run the following command:
Restart your PC and you're done!