I have a 30 month old MacBook Pro (the SantaRosa line from June 2007)... And was still using the original battery up until 3 days ago. Its capacity suddenly dropped from 83% down to 45%, so I took it to an Apple store, they did a diagnostic, and without question told me the battery was defective, and just gave me a brand new battery with only 1 loadcycle on it. So today I decided to calibrate it, had it charged up, unpulgged it and let it run until it was 'supposed' to go to sleep... It had 0% left on it, the screen shut off, and the sleep light was just starting to dim, when I heard the hard drive go BZZZZZZZWheeeeeeeeeeooooooooo... (As if one pushed and held the power button, aka hard shutdown). It seems it didn't have enough reserve capacity to let it go to sleep, so instead of waiting the 5 hours (as it wasn't sleeping, and pressing the button on the battery showed no lights at all), I decided to plug it in right away. Would it be a good idea to calibrate again, or simply wait a month or so and do it again then? When I turned the computer back on, it didn't even resume at my desktop, so not only did it not get to sleep properly, it didn't even have a chance to write the memory to the hard drive, and now the actual battery capacity in Coconut battery is showing up 95%, 5253mAh Just curious, as 30 months ago when I first got my original one, it calibrated properly and didn't completely die when it got to reserve capacity... Thanks!