VirtualBox
Due to limitations with VirtualBox on Windows, it is highly recommended to use a Windows account with admin rights to run Genymotion Desktop.
If admin rights are not possible, and errors "Unable to start a device" or "An error has occurred while trying to create a virtualbox host-only network interface" occur, try the following: 1. Log in to Windows with an admin account. 2. Open VirtualBox and go to File > Host Network Manager.... 3. Delete all the excess VirtualBox host-only ethernet adapaters. There should be only one left. 4. Reboot your PC and log in with the standard user account. 5. Run Genymotion.
If the error still occurs, repeat steps 4-5.
QEMU
QEMU support is still experimental and buggy on Windows at the moment.
Until QEMU support is stable, use the VirtualBox hypervisor on Windows.