I installed 10.5.3 about an hour ago, and about 5 minutes ago my macbook just shut off instantly while I was on safari and ichat. When the computer shut off, the isight light blinked on and off, so I shut the screen and removed the battery and reset the power management (held power while battery and AC power is off). The computer will NOT boot what so ever, the only thing that happens when I hold the power button is that the isight's green indictor blinks repeatedly while the power button is depressed. I have a 2 gig ram upgrade but Im thinking this is a power/lb issue or something big. Any ideas?