hi there I have a macbook pro which suddenly has begun shutting down without warning either just after the initial chime or shortly thereafter. it only happens when it's running on its battery - and happens even though there's still plenty of power left. I have tried starting it up again (on the battery) - but it just keeps on shutting down until I connect it to power. a friend of mine suggested it has something to do with "bios" - and that it's relativily simple to fix. and I would so love not to have to have it sent in to mac for repair and being without it for several weeks - so please, please - someone - what's happening - and can I fix it?