This post is Part 2 of the Dell Studio Screen Brightness Control Problem in Ubuntu. In that post, I mentioned how you can solve this issue by making an edit in the /boot/grub/menu.lst file. But recently, I upgraded my bootlaoder to GRUB 2. Many people would eventually do so in the near future. As I've mentioned in that post, editing GRUB 2 files isn't as straightforward as editing menu.lst.

Here's a simple solution to get your Dell Studio brightness control buttons working if you are using GRUB 2-

1.Edit the GRUB 2 default options file by running the following in a terminal

sudo gedit /etc/default/grub

2.Look for the line-

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

and change it to-

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash noapic"

3.Now update GRUB by running-

sudo update-grub

4.Reboot your laptop. Your brightness buttons should work perfectly fine now.

Basically, you've made the same edit to the GRUB configuration file here too but the method to do it with GRUB 2 is slightly different.