I don't have very good luck when installing vBox form the software 
center, Im sure others do, but I just don't.  So i would recommend 
removing your current install and then installin from the site.
 
Then do a search in nautilus in your FileSystem for virtualbox and remove any leftovers.
 
Then install dkms and build-essential
 
Then download per site instructions.
https://www.virtualbox.org/wiki/Linux_Downloads
Last step, install Extension Pack
https://www.virtualbox.org/wiki/Downloads
Code:
sudo apt-get remove --purge virtualbox
Code:
gksudo nautilus
Code:
sudo apt-get install dkms build-essential
https://www.virtualbox.org/wiki/Linux_Downloads
Last step, install Extension Pack
https://www.virtualbox.org/wiki/Downloads
