[Denis Dyagilev]

Если Вы устанавливаете ОС x64, то это и не будет работать, требуется поддержка HAV, которую не может обеспечить виртуальная машина Hyper-V.

Более того:
Do not run other hypervisors (open-source or commercial virtualization products) together with VirtualBox! While several hypervisors can normally be installed in parallel, do not attempt to run several virtual machines from competing hypervisors at the same time. VirtualBox cannot track what another hypervisor is currently attempting to do on the same host, and especially if several products attempt to use hardware virtualization features such as VT-x, this can crash the entire host. Also, within VirtualBox, you can mix software and hardware virtualization when running multiple VMs. In certain cases a small performance penalty will be unavoidable when mixing VT-x and software virtualization VMs. We recommend not mixing virtualization modes if maximum performance and low overhead are essential. This does not apply to AMD-V.