I have a six-month-old Macbook pro (2.16 GHz). It is by far, the best computer I have ever owned and used, but twice during this period, the battery has died on me ... sort of. It's the now-classic "charged battery laptop that shuts down when unplugged" syndrome. Sometimes this happens immediately after unplugging the machine from the wall, with a 100% battery charge. Sometimes it happens only when the battery reaches a specific charge level after being unplug. I have had both. When you reach this point, trying to restart the laptop on the battery immediately shuts down the computer after a fibble attempt at startup. You can't even go into single user mode.

I have looked around the web for a solution to this, but nothing. Apple recommends resetting the power manager, and the PRAM. For me, these have not helped. I have run Applejack to remove all cache and repaired permissions ... nada. Some blogs state that the only solution is to have Apple replace the logic board or some other components, but since that would be a long process for my machine (which belongs to my employer), I did not want to do this.

Each of the times this has happened, I have been able to bring the computer and battery back to normal operation, yet I have not come across anyone explaining similar instructions, so I thought perhaps posting it here could help a few.

The first time this happened to me, a couple of months ago, I was at the office. Out of desperation I asked a coworker who has an identical machine to swap batteries for the morning. Believe it or not, this worked. My battery behaved normally on his machine and his worked just fine one mine. Swapping them back and forth a couple of times did the trick. Yes it took a couple of times for some reason. Each time I reset the power manager and plugged and unplugged the machines several times.

The second time it was on a Saturday evening at home, where I had no access to a second similar machine. This time, again out of a desperate attempt at something magical, I realized that, even though the machine would immediately shutdown when unplugged, it would not do so if I closed the lid and put it to sleep. Like that, it would stay on indefinitely. So I left it like that all night to push it beyond its shutdown charge limit. The next morning, the machine was at 87% charge when I lifted the lid back up. It did not shut down right away, but about 10 minutes later or so. So I plugged it back in and rebooted, closed the lid again, and unplugged it for another couple of hours. When I opened the lid again, it never shut down again. I put a CD into the slot and ripped it in iTunes several times until I drained the battery. It has behaved normally since.

Hope this help some of you get your laptops back up.

[robg adds: I would strongly advise warranty service for a six-month-old machine exhibiting these symptoms, but if you're in a crunch, perhaps these tips will help.]