"No Batteries Available" displayed in upper corner of screen
My 2.4ghz macbook had the dreaded X intermittently appear in the battery icon in the upper right corner of the screen, and the dropdown would read "no batteries available." This would be the case even with a good battery in the computer. If unplugged, the computer would often run for a minute or two before abruptly shutting down. Gradually, this went from an occasional occurrence to the status quo.
Is this a good question?