Fix for brightness issue in Ubuntu 13.10- 1 min
In Ubuntu 13.10, I found that I was unable to change the brightness either by using the brightness keys or moving the brightness slider in System Settings. To fix the issue, I had to change the file
/etc/default/grub to reflect the following:
GRUB_CMDLINE_LINUX="quiet splash acpi_osi=Linux acpi_backlight=vendor"