Fix your laptops brightness function keys operating properly in Hardy
Before doing any changes you need to take backup of existing files
Now you need to download the following files in /etc/acpi/ directory
Download video_brightnessup.sh from here
Download video_brightnessdown.sh from here
After replacing these scripts
No reboot or logout required, simply press your function combination on your laptop to change brightness. Try to press FN + Up/Down Arrow.
Credit goes to AaronMT