I've moved this post to a thread of its own. Originally posted in http://ubuntuforums.org/showthread.php?t=2145241
Can you provide some more information? Specifically:
1. The make and model of your computer.
2. The version and flavour of ubuntu that you are using?
3. Your current kernel boot line:
4. Your video card and driver:
5. Your backlight interfaces and their values:
lspci -k | grep -iA2 VGA
for i in /sys/class/backlight/*; do echo $i;cat $i/brightness;cat $i/max_brightness;done