Automatically changing screen brightness

Hi guys, mine is a very unusual predicament, I just bought a new Dell N311z

I've noticed that when the brightness of my screen is anywhere between maximum and minimum it automatically decreases or increases on will, without me doing anything.

I've also noticed that when the background on the LCD is of a darker colour the brightness decreases and when it's a lighter background the brightness increases itself.

I've tried everything from disabling the ambient light sensor to calling up Dell customer care and after having spent 3 hours on doing what they made me do it still hasn't fixed my problem. I reset the laptop to the factory settings, i reinstalled all the drivers as well.

I have a Dell N311z. Windows 7 Home Premium 64bit.

I'd really appreciate your reply.


Thanks in advance.

I've heard of screens that adjust the backlight brightness depending on the content of the screen - the idea is to "fake" a greater contrast range with whiter whites and (particularly) blacker blacks.
I suspect that your screen is doing exactly this and it isn't a software issue at all...I don't know your machine but wonder if there might be a BIOS setting to disable this feature, maybe...