I have a macbook C2 2Gig w 1gig of RAM. Every so often (usually right after disconnecting from the power cable, which is weird), I will hit cmd option eject to put it to sleep and nothing happens. I select sleep from the menu, and nothing happens. Even closing the lid doesn't work. If I select shut down, nothing happens. The only way to shut the computer off is to hold the power button until it turns off. I found some answers before, which involved deleting some files from the preference folder, and it seemed to work for about a week, but the problem popped up again yesterday. Any suggestions?