VirtualBox working... but /sbin/vboxconfig missing?

This is not a problem that I've seen too often with VirtualBox, but there are instances when an installation will "hiccup". The /sbin/vboxconfig file is just a symbolic link, so you can resolve it yourself if you'd like:

0. Open Terminal (if it's not already open)
1. Create the symbolic link:

   sudo ln -s /usr/lib/virtualbox/postinst-common.sh /sbin/vboxconfig
   

   ^{Note: The use of sudo here ensures the link can be written and is owned by root.}

Be sure that all of the VirtualBox packages are running with the same version number to reduce the risk of errors, particularly with the "Guest Additions CD Image".