Ubuntu 8.10 in a Sun VirtualBox on a Windows XP Host

[4] For the first time, the SUN VirtualBox Guest Additions did not work after a successful install and restart.

More specifically, the video drivers were limited to 640x480 and 800x600 resolutions.
Doing some digging around, this is specific to Intrepid (8.10) as it worked on all previous versions including Hardy Heron (8.04).

So the solution is....

Well, edit your xorg.conf: sudo gedit /etc/X11/xorg.conf

With the xorg.conf opened, edit the following sections w/ the information below:

Under the "Device" section, find the line Identifier "Configured Video Device"
Add the following line right below:

Driver "vboxvideo"

Under the "Screen" section, replace the default 3 lines with the following (adjust as you wish):

Identifier "Default Screen"
Device "VirtualBox graphics card" Monitor "
Generic Monitor"
DefaultDepth 24
SubSection

"Display"
Depth 24
Modes "1024x768"

EndSubSection