Hello Linux Geeksters.
This issue occurs on Ubuntu 12.04, running on Hewlett Packard (HP) Pavilion laptops.
If you get a black screen, whenever you start your laptop and before getting the Login Screen, this article may help you.
To fix the black screen problem, do this:
$ gksudo /etc/default/grub
Find the GRUB_CMDLINE_LINUX=” “ line and modify it to look like this:
GRUB_CMDLINE_LINUX=”acpi_osi=Linux acpi_backlight=vendor“
Update Grub:
$ sudo update-grub
After the reboot, your back light problem should be solved.