Like the title says, my MacBook has developed a tendency to lose power. It has done this 4 times, twice with power adapter plugged in, twice without. Battery has been anywhere between 43% and 82% full. I have tried repairing permissions and resetting power management. Every time, I have been using my Airport - one streaming video, one loading new page, one loading the HD Talladega Nights trailer, one while printing. Three times, when I try to turn the computer back on, it will begin, making the gong-ish sound for a split-second, then shutting off. To fix it in this case, I must hold the power button down for about 5 seconds (battery in). It will start squealing, then the LED will flash very fast. I release the power button, and turn it on as normal. I figure it's either something really small (run a quick fix), or really big (replace computer). HELP!!!!!