I purchased a 15 MacBook Pro back in December of 2008 (currently still running Snow Leopard) which is still performing well with no serious problems. However, I have noticed in recent months that at night when I am watching a movie or video if I turn off the lights in the room where I keep the computer the screen will dim slightly and the brightness indicator will decrease about two clicks. If I manually increase the brightness the screen remains a bit dim even if I turn the lights back on. I made sure in display preferences that the box that says automatically adjust brightness as ambient light changes is definitely UNCHECKED, disabled. Also, my MacBook Pro is always on electric power--not battery---when I am using it at home. If I turn on the lights and shut down the computer and then restart the screen brightness returns to normal. If I turn off the lights the screen dims again. I would appreciate any suggestions from the community here on how I can perhaps fix this minor but nevertheless annoying problem. Thanks in advance.