Hi MR Neighbors, I am having a problem with my Macbook Pro where it will randomly shut down while on battery power. No low-battery warning, no nothing, just dead. Subsequent attempts to turn the computer back on result in the classic Apple "chime," but the computer never gets to its gray screen. The situation is alleviated by plugging in the power connector, as long as the power connector is plugged in. Pertinent info: I recently upgraded to 10.8 Mountain Lion. After these random shutdowns began, I downgraded to 10.6.8 from a backup, but the problem wasn't fixed. My battery is a NuPower replacement battery. The problem doesn't occur on my old Apple battery (which doesn't hold much charge, but at least gets to the end of its charge like normal) This is a Macbook Pro 3,1 (2007) I've tried resetting the SMC and PRAM but these haven't fixed it. If anyone's had any similar problems or has any suggestions, I would greatly appreciate them. Unfortunately I am outside of my 1-year warranty on the NuPower battery, and well outside my Apple warranty. Thanks!