Battery dies at 50 percent... only after i recalibrated it

Ever since i did my second battery recalibration, my batteries health (through iStat pro) has gone from a 97% to a paltry 64%. Due to this when my charge has around an hour left (40% charge remaining area), the battery literally just dies out on me, going critical almost instantly, running on reserve battery power, then shutting down without warning (5 seconds after the critical message pops up). I did record it with a screen capturing tool, but since the battey shut down, the files are gone.

Is this a problem with the Power management unit, the battery, or the computer itself? Battery life is crucial to me now, as i need to edit on the fly with both protools and final cut in college... and it has already cost me one grade.