I’m back on Linux, back in trouble as well. Ok so downloading and installing the latest deb file for VirtualBox doesn’t work out of a box.
I found this in the VirtualBox forum. It turns out you need to install these packages first.
sudo apt-get install dkms build-essential linux-headers-generic
Then install the deb file
sudo dpkg -i virtualbox-4.2_4.2.10-84104~Ubuntu~quantal_amd64.deb