We just got a tablet pc from a friend - doesn't include what kind - some generic 7" tablet pc that has Android 4.0 Ice Cream Sandwich system. My husband was playing around on it and selected an icon that looked like a sunshine and the screen went black / blank. I've read other users had this problem in earlier versions of Android, but not 4.0. I have used all the workarounds to try to change the brightness blindly with no success. I can power it down and power it back up, but after the startup screens disappear, the screen is blank.