I've had my MacBook since July 2007, but purchased a new battery on February 1st of this year and lately my computer has been giving a message that says "Service Battery". I really don't understand what's wrong since my battery is not old, and it never had that problem in the years that I had my old battery. the nearest Apple store is 25 minutes away and I really don't have much time to go there, so is there anything I can do on my own before I get it checked out?