Notebook: Dell INSPIRON 1564. There was no such problem in Ubuntu 11.04. Don't upgrade to 12.10, you will encounter ugly interface problem (see here).
Noticed from here: askubuntu, a method was proposed, which was to modify a line in
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor acpi_osi=Linux"And then update and reboot
sudo update-grub sudo reboot
Although I tried the same, I don't confirm this will definitely work. My experience is, if you tap slowly one at a time until it changes the brightness and show the notification, then proceed, it will be okay. If you are stuck in such freezing state, any keyboard combo can't save you out.
Reset brightness to lowest on reboot
That is what I wanted to do. Ubuntu didn't save (or the video driver) the last-time configuration of brightness. (link)
The solution, I too confirm, is to add a local script to be executed on reboot. Here is the excerpt.
sudo vi /etc/rc.local
Add the following due to your folders under
/sys/class/backlight (you might need play around with it)
echo 0 > /sys/class/backlight/acpi_video0/brightness exit 0
My machine uses a default video driver (non-proprietary) and the video card ATI RV710.