Comment 4 for bug 1417722

I was able to fix that, with the following steps,
first of all; I had virtualbox 5.0 beta installed, then I removed it used the following command
sudo dpkg -r virtualbox

I figured out if I only use "dpkg -r" or "dpkg --remove" it will not run "postrm". it means that the configuration files remain the same.
but using "dpkg --purge" removes the package and it runs "postrm". it will clear out all the configuration conflicts. After that I was able to do a clean install using "sudo apt-get install virtualbox".

I hope this comment help.
cheers.