xxxxxxxxxx
//For me I solved it by setting up a MOK key
//It solved the issue since when I ran
$ sudo dmesg | grep -i vboxdrv
//It brought back the version number
xxxxxxxxxx
wget -q -O - http://download.virtualbox.org/virtualbox/debian/oracle_vbox_2016.asc | sudo apt-key add -
xxxxxxxxxx
Solution seems to be to not install the virtualbox package that comes with Ubuntu. Following the steps to add a 3rd party repository as shown here, then installing the virtualbox-5.1 package appears to get things working with no further actions required.