My MacBook 2010 was having an intermittent shutdown issue. It would stay on for 30 minutes, then just shut off. Nothing would be stored in the console logs which indicated anything was wrong with any programs running.
I opened up the machine and when I got to the right corner near the trackpad, it kind of popped open. The battery had expanded on the right side (near the connector) and cracked the plastic case that hold the battery contents and was pushing against both the trackpad and the case. The battery was "dead" for quite some time which I never did anything about. Seeing this, I removed the battery, and the intermittent shutdown's have thankfully ceased.
End of Story.
