I had an issue with my resolution. The screen when i first installed Ubuntu 8.10 was visible, but half the screen was missing. Reading about it, my screen was what I could see however the OS was setting a virtual screen size way bigger.

Fiddling with the resolution just totally assed up the display making it unreadable.

However, I found one method which does work, I guarantee.

Run .... gksudo gedit /etc/X11/xorg.conf in Terminal.

Scroll around until you find the screen section. After the device label, insert a Display subsection, specifying the resolution needed. In my case I required "1280 X 800"

Code:
Section "Screen"
     Identifier "Default Screen"
     Monitor    "Configured Monitor"
     Device     "Configured Video Device"
     Subsection "Display"
         Modes      "1280x800"
     EndSubSection
EndSection
The red part is what I added in. After a reboot, the screen setting is now perfectly set.