I have had my ibook for about a year and half its 10.4.7 of OSX and for some reason every once in awhile the screen will de-illuminate i can see whats on the screen barely i will just close it wait for the hibernate light then open it back up and its working fine and then in some cases it will just shut off in which case i have to release the battery and put it back in and then start it up and it turns on again. anyone know whats going on