This is a known bug with legacy versions of Genymotion Desktop. Make sure to use the latest stable version of Genymotion Desktop.
If upgrading still does not help, stop Genymotion, open a terminal and try logging in with gmtool:
Important
You need an active Genymotion account to use this workaround. If you don't have an account yet, you must create and activate one here.
Windows
C:\Program Files\Genymobile\Genymotion\gmtool config --email EMAIL --password PASSWORD
Linux
~/genymotion/gmtool config --email EMAIL --password PASSWORD
macOS
/Applications/Genymotion.app/Contents/MacOS/gmtool config --email EMAIL --password PASSWORD
Then, launch Genymotion again.
Windows
Windows for IoT
Genymotion Desktop is not compatible with Windows for IoT, such as Windows 10 IoT Entreprise and Windows 10 IoT Standard.
Please use a supported Windows edition.
Hyper-V
Note
It is possible to use QEMU instead of VirtualBox: QEMU uses Hyper-V and it is a possible alternative if you cannot disable Hyper-V for some reasons. However, please note that QEMU support is still experimental and has severe performance issues on Windows.
This may be caused by Hyper-V which conflicts with VirtualBox. Try to disable Hyper-V. For detailed instructions, please refer to Genymotion Desktop and Hyper-V
Laptops with discrete GPU
Some laptops have a dual GPU: one integrated Intel iGPU and one discrete NVIDIA/AMD GPU. This type of hardware is known to cause issues on Windows; mainly because the system fails to recognize Genymotion as a high performance, high requirements application.
Therefore, it tries to run Genymotion with the low-profile Intel iGPU which does not meet Genymotion requirements.
To workaround this, you need to force Windows to use the high-profile discrete NVIDIA/AMD GPU globally. To do so, please refer to How to force Genymotion Desktop use the high performance discrete GPU on laptops?
Other
If none of the above worked, try to uninstall and purge Genymotion Desktop and re-install it. See How to uninstall Genymotion Desktop completely (purge)?