Ubuntu 12.04 brightness reseted to zero after reboot

After a day using Ubuntu 12.04 on my Acer Aspire 4530, I noticed that every time I reboot, the brightness setting is reseted to zero.  Initially, I thought that there is a problem again between Ubuntu and my NVIDIA driver.

Googling showed that many users encountered the same issue like me, especially laptop users.

There are several tips that I tried... but none are working.  Anyway, I'll share the tips here because it might work on you guys.

Solution 1:
1. Open Terminal

2. run the following command to edit the content of grub

  sudo gedit /etc/default/grub

3. modify the line with GRUB_CMDLINE_LINUX_DEFAULT so that it will look like below:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"
4. save and exit
5. run the following command to update grub
    sudo update-grub
6. restart ubuntu with the following command
    sudo restart

Some users were having their problem fixed with solution 1.  But now mine.  Thus, i tried other solution

Solution 2:
1. Adjust the brightness that you like.
2. Open Terminal
3. Find the value of your current brightness by running the following command
    cat /sys/class/backlight/acpi_video0/brightness
    If you encounter the error "cat: /sys/class/backlight/acpi_video0/brightness: No such file or directory".... it means that your brightness setting is not in acpi_video0 folder.  You can find the correct folder by running the command below.
     ls /sys/class/backlight/*/brightness
     now you can run again the 'cat' command using proper folder.  In my case, the command looks like below
     cat /sys/class/backlight/acer-wmi/brightness
     The 'cat' command will return a numeric value which is the value of your current brightness.  Remember that value. Let say the value is 7.
4. Run the following command to edit the content of rc.local

  sudo gedit /etc/rc.local

5. Add the following command below just above 'exit 0'

    echo 7 > /sys/class/backlight/acpi_video0/brightness

    where 7 is the value of your current brightness

    In my case since the folder of acpi_video0 is different, then, the command becomes

    echo 7 > /sys/class/backlight/acer-wmi/brightness

6. save and exit7. restart ubuntu with the following command
    sudo restart

Does it fix your problem?  Well, not in my case.
Then, I do trial and error and apply solution 3.

Solution 3:
1. Follow Solution 2 from step 1 to 4.

2.Add the following command below just above 'exit 0'

    echo 7 > /sys/class/backlight/acpi_video0/brightness

    sleep 10

    echo 7 > /sys/class/backlight/acpi_video0/brightness

    where 7 is the value of your current brightness and asumming acpi_video0 is the correct folder.

3. save, exit, and restart ubuntu

Magic.... it solves my problem.  This solution 3 might not be the optimum solution.  But as long it solves my problem.  I will stick to it at the moment.  Hope it can help you guys as well.