After kernel upgrade vbox fails to start

[Steven Davies-Morris]

I'm on Ubuntu 8.04 (my host o/s).  Vbox 1.6 has been running fine with 
WinXp as a guest o/s.  I upgraded my kernel with the updates that came 
over the holiday weekend and wham...something is broken.

Here's what I get when I try to start my virtual:

Failed to start the virtual machine Win2KOEM.

VirtualBox kernel driver not installed. The vboxdrv kernel module was 
either not loaded or /dev/vboxdrv was not created for some reason. 
Re-setup the kernel module by executing '/etc/init.d/vboxdrv setup' as root.

VBox status code: -1908 (VERR_VM_DRIVER_NOT_INSTALLED).

Result Code: 0x80004005
Component: Console
Interface: IConsole {d5a1cbda-f5d7-4824-9afe-d640c94c7dcf}

So I open a terminal.  Become su and try to resetup the kernel per 
instructions.  Still no joy:

sdavmor at spock:~$ sudo /etc/init.d/vboxdrv setup
sudo: unable to resolve host spock
* Stopping VirtualBox kernel module 
         * done.
* Recompiling VirtualBox kernel module 

* Look at /var/log/vbox-install.log to find out what went wrong

So I look at it:

sdavmor at spock:~$ cat /var/log/vbox-install.log
Makefile:127: *** Error: unable to find the sources of your current 
Linux kernel. Specify KERN_DIR=<directory> and run Make again.  Stop.

...er...what has happened?  And more to the point, where am I supposed 
to specify KERN_DIR=<directory> (etc etc)?
-- 
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