Brightness reducer in Energy Saver is stuck on

[Brilopad1]

For some reason my imac is reducing the brightness of the display when I don't even have the brightness reducer button selected. No matter what I set it to the display always dims after a couple minutes. This is really annoying when watching movies. Does anybody have any idea why my imac is doing this and how I could fix it? I'm running Tiger 10.4.11.

 

[skd]

my MBP is doing the same thing.....

 

[lorien]

Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU like Mac OS X; en) AppleWebKit/420.1 (KHTML, like Gecko) Version/3.0 Mobile/3A109a Safari/419.3)

In display settings under System Prefs check if the brightness according to ambient light box is checked. If not, check if the automatically dim display setting is on in Energy Saver in System Prefs

 

[Brilopad1]

I can't find the "brightness according to ambient light box" under displays in system preferences, and the "Automatically reduce the brightness of the display before sleep" button is turned off. I have my display set to sleep after 15 minutes of inactivity and the computer to sleep after 1 hour of inactivity.