Turning off auto-dim in Dell laptops and win7

I had a Dell laptop with Win7 that the user was complaining that the screen was going black. I quickly realized it was not the screen, but a setting. When you put your hands on the keyboard, the screen would dim. If you put your finger over the sensor, it would (obviously) go black. I hunted around for quite a while, but found a simple fix:

function

This turned the auto-dim function on and off. I am thinking that he inadvertently set it when he was trying to change his resolution.