Here's a funky issue: Twice, my iBook's backlight spontaneously turned itself off while I was using it. The computer would keep running and the image on the screen was still faintly visible, but the backlight would turn itself off. The backlight wouldn't turn back on unless I put it to sleep and woke it. It's not the hinge, because moving the screen to a different angle didn'd do anything. The video is not scrambled, either. Is it yet another logic board failure? Another hardware problem? Software? I have a 900 MHz iBook G3, 12" screen, combo drive. Thanks in advance.