i usually leave my iBook (14-inch, G4 1.33 GHz) to sleep at night and i rarely shut it down. well the other morning i picked it up and the light was flashing like normal for sleep. then i opened it up and the light went off but the screen stayed black. i pressed the space bar etc. but nothing happened. then i pressed the power button and it started up just like it would have if i'd shut it down the night before. then this evening i'm in class taking notes and i'm typing away then all of a sudden my computer is off. weird. then i turned it on and it started up just like i'd shut it down. this second time it happened when i started it up and everything booted it was like the power management unit had been reset. the date was set to 1969, time was 5:00 pm etc. i didn't do the key command to reset the pmu. what's going on here?