Ok, at first I had this strange problem where my Macbook would charge up the battery and show it at 100% in the menu icon in OS X and the battery would also light up all the LEDs when you checked the power on it. Only thing was the second you unplugged it, the Macbook would power off. You could try to restart it and power it back on with battery power and it would maybe spin the hard drive and the screen would blink on for about a second before going dead. I sent it in and Apple fixed it to where the battery seemed to work fine. Now it seems it will randomly cut off while on battery power every once in a while. It has done so three times so far all with at least 45 minutes of battery power left on the icon in OS X. It has never turned off on AC power, only on the battery. Any idea if I should check with Apple again to get it repaired or could this be some kind of software issue?