Paul is trying to create a version of his hard drive image that can run in VirtualBox. The image uses VHD and he's having issues with VirtualBox reading it. It does do it with Windows 7. But he gets a "no bootable medium" message. Leo says that there are more standard formats other than VHD. Most virtual platforms look for ISOs with a native format of VDI. He also wants to be sure that the BIOS is using the UEFI format.
From Sophie in the chatroom - there is an “enable UEFI boot” in VirtualBox. That could maybe be the solution.