Hello all, I have a problem with my Macbook Pro. I usually keep it plugged in and on occasion use it when I sit on my couch or elsewhere unplugged. Lately, when I have drained the power down to ~40% remaining, my Mac will just shut off as if there is no power left. There is no "low battery power" indication or anything and it doesn't go to sleep, it just turns itself off. Does anybody have experience with this or have any idea what to do? It has happened twice now and I am concerned that there is a problem with the battery because it reaches the 40% level rather quickly...after only about an hour. Thanks.