Genymotion gave me same error when I re-installed VirtualBox.
Turns out that the 1st time VirtualBox was installed in: C:\Program Files\Oracle VM VirtualBox and this was in registry (for genymotion VBoxPath)
and 2nd time it was installed in "C:\Program Files\Oracle\VirtualBox".
So, to fix this I had to change the path in registry at path:
HKEY_CURRENT_USER\Software\Genymobile\Genymotion\ for value "VBoxPath" to: "C:\Program Files\Oracle\VirtualBox\\VBoxManage.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Oracle\VirtualBox for value "InstallDir" to: "C:\Program Files\Oracle\VirtualBox\"
Once I set the correct path and logged off and logged back on, it started working again.
Log off/log on or reboot is required to reload the registry.