Problem:
On my Windows 10 machine and after installing Docker, I was unable to start any of my Oracle VirtualBox VM machines, they all throw the same error: VERR_NEM_VM_CREATE_FAILED
Solution:
I've uninstalled Docker first, then disabled "Virtual Machine Platform feature" from my Windows machine, restarted my machine, and then I managed to start my VirtualBox VMs without any issues.
From Run: optionalfeatures
Untick "Virtual Machine Platform"
Then restart your Windows machine.