My MacBook Pro has developed a strange problem recently that has me somewhat concerned and annoyed, as I would like to use my laptop without it having to plugged in all the time. A vast majority of the time it's on a stand with an external keyboard and mouse, running off MagSafe power. However, whenever I disconnect it the system immediately shuts down completely. The battery indicator lights show that the battery is fully charged, but it won't turn on until it's plugged in again. When I press the power button I can hear the HDD spin up briefly, but it winds down again and nothing happens. I haven't calibrated the battery recently, but I don't think that could be a cause, and calibrating it now is out of the question since the system won't even boot off of battery power. Any tips/ideas? Thanks!