If you run into the following error when attempting to start a VirtualBox VM
NS_ERROR_FAILURE (0x80004005)
Component: Machine
Interface: IMachine {5eaa9319-62fc-4b0a-843c-0cb1940f8a91}
Kernel driver not installed (rc=-1908)
You can run the following command to correct the problem:
sudo kextload /Library/Extensions/VBoxDrv.kext/