Just wanted to let anyone else having this problem know that you need to install your kernel headers to correct this problem. You can install the correct headers for your system via the terminal with this command: "sudo aptitude install linux-headers-$(uname -r)" followed by this command to install the vbox kernel driver: "sudo /etc/init.d/vboxdrv setup"

I found this information in this thread, courtesty of bodhi.zazen: http://www.ubuntu-forums.com/showthread.php?t=458494 I happen to be running the PUEL version, but I believe this information would also pertain to the FOSS version.