When I installed Ubuntu on my Dell Studio 1555, I faced more than one problem. I forgot to mention about this issue in my last post. In Ubuntu, the brightness control buttons of my laptop refused to work. They worked for the first 30 seconds or so after startup and after that the brightness and wireless buttons refused to work. The brightness slider too was unable to control the screen brightness. Brightness control is a very important feature and its something you can't live without if your laptop runs on battery power very often.
As usual, the reason I'm writing this post is because I did find a solution to the issue and managed to get the buttons working. Here's the simple solution-
1.Edit the GRUB menu.lst file by running the following code in the terminal
sudo gedit /boot/grub/menu.lst
2.Look for the line
# defoptions=quiet splash
and change it to
# defoptions=quiet splash noapic
Save the file and close the text editor.
3.Now update grub by running-
4.Reboot your laptop. Your brightness buttons should work perfectly fine now.
The GNOME Power Manager offers quite a bit of configuration but at times you feel the need for some more configuration options. You can make those customizations by editing a few keys in the GNOME Configuration Editor. Be careful, you should edit a key only if you are sure about what you are doing. To open the configuration editor, run 'gconf-editor' in the terminal. The GNOME Power Manager keys can be found under /apps/gnome-power-manager. You can control settings like how much the brightness is reduced when on battery power and actions to perform under various circumstances. This way you can make more customizations than the GUI offers.
Note: This method will only work with the GRUB legacy bootloader. If you are using GRUB 2, wich is very likely after the release of Ubuntu 9.10 Karmic Koala, you should have a look at part 2 of this post- Dell Studio Screen Brightness Control Problem in Ubuntu-Part 2