I posted about this in an old existing thread in the Mac OS X subforum, but I think that it might be more relevant here in case it's hardware related. I just bought a 15 inch SR MBP and my display sometimes dims after a certain amount of inactivity. As soon as I move the mouse or press a key, the display returns to normal brightness. This is not the display going to sleep where it's completely off. I have unchecked the power option setting to dim the display just before the display goes to sleep. I can't find any other setting in the OS to control this. This is my first Mac, and it's certainly humbling learning a new OS since I feel very comfortable with Windows machines.