Hello! My DVD drive has been screwy lately -- it will play some DVDs, but not others -- perfectly good ones, even after having played the very same ones. Also, burning CDs -- sometimes it will, sometimes it won't. Is there any kind of maintenance I can do? (Can't afford to get a new one right now...) Stats: MacBook Pro, first generation. OS 10.4.11 Anyone else having the same issues? Thank you!