Every time I play music on battery, I usually turn my screen's brightness all the way off and encounter errors. My MBP is set to turn off the display after 5 minutes. The problem happens when the 5 minutes has passed and I try to press a key, move the trackpad, or click it will all do nothing. I try to increase the brightness but it does nothing. I close my lid and wait till it sleeps then when I wake it up the brightness will be set to however much I turned it up or down when the screen was black. This has to be a software bug within Lion as when the original hard drive with SL on it didn't give me any problems. It is really pissing me off as I just spent $3000 on this laptop last friday.