Hello all,

I had this error on a reboot on Ubuntu 16.04 after uninstalling VirtualBox using:

sudo apt-get remove virtualbox-\*
sudo apt-get purge virtualbox-\*

In order to fix it I had to:

1. Delete virtualbox-guest-utils & virtualbox-guest-x11 VBox in /etc/init.d.
2. Delete all references to Virtualbox in /etc/X11/Xsession.d/.
3. Remove all the kernel modules left in /lib/modules/4.4.0-45-generic/kernel/ubuntu/vbox (please not that your kernel’s folder name in /lib/modules can be different. Run uname -r to identify your current kernel name).

After a clean uninstall I suggest you to install VirtualBox using apt with:

sudo apt-get install virtualbox

Hope this helped you,
Have a good day.