I have had my macbook for 2 years. It is still using the same battery as the day that I got it. I have not had any battery problems, and it has always worked flawlessly for me. Today, my computer has just shut off twice. It said the battery was at 89 percent when it shut off, and I just plugged it in, and it now says 0 percent. Any ideas on what is causing this problem? Any help would be appreciated.