Sometimes, you have to use VMware or VirtualBox, but you have Hyper-V installed on your machine (usually to develop Windows Phone application). VMware or VirtualBox can’t run side-by-side with Hyper-V. They have different type of Hypervisor.
If you want to run VMware/VirtualBox and Hyper-V on same machine (but not side-by-side), you can set-up your hypervisor launch options in BCD. Simply, open Administrator’s Command Prompt (Run as administrator) and then:
Disable Hypervisor Launch Options: to run VMware or VirtualBox
C:\WINDOWS\system32>bcdedit /set hypervisorlaunchtype off The operation completed successfully.
Enable Hypervisor Launch Options: to run Hyper-V
C:\WINDOWS\system32>bcdedit /set hypervisorlaunchtype auto The operation completed successfully.
Don’t forget to reboot your machine. And voilà: you can use Hypervisors that you want.