MacBook Unexpected Shutdowns

[umrawr27]

I have a MacBook that's about two years old (I got it in October 2006). I have a problem where it will be fully charged and then when it gets about 85 - 80% it will just shutdown without notice.
Any ideas of what might be the problem? Should I take it to the genius bar?
Thanks!

[TwinCities Dan]

Sounds like your battery is funky, can you re-calibrate it? Otherwise, yea, bring it in...

[showtime]

do you have applecare on your macbook?