I use ATItool to change monitor brightness and I have a profile called Dark that is a copy of the default profile except the gamma+brightness are turned down. ATItool doesn't allow loading the Dark profile while the default one is on - the Load button doesn't become active - when the main window is up. But I can load it via right clicking the tray icon. It doesn't bother me much, but it is a bug of sorts. I think it has to do with the profiles having the same clock speed. I created the Dark profile by copying the default one then just changing the gamme/brightness settings and saving it as Dark. I have ATItool .24, a 9500->9700, and WinXP SP2.