I have a Late 2006 MBP (This one). I don't use it much (it's for travelling). I leave it plugged into the wall or unplugged for weeks at a time without using the battery. Since I bought it, I have gone through 4 batteries, including the one that came with the machine. That's over $500 in batteries! The computer says "Batteries not Charging" with an X in front of the battery icon. Or it says "No batteries available". I'm about to buy my 5th battery. What should I do this time to prevent it from dying like the others? Or is it a problem with my computer, and not the battery?