Good day, My mac (unibody aluminium) is turning off suddenly when is not charging. Sometimes goes off when is 50% batt remaining sometimes around 78%. The battery is new, It has 31 cycles, 86% health. I already reseted the computer (taking battery out and pressing the power button 5 secs) but is not working. Some articles says it may be the OS (i have snow leopard). What should I do?