I love my Macs to bits but one thing which always bothers me is the power management. It happens too often (i.e. ever) that when I lift the lid of my Mac to wake it from sleep I get a black screen with a perpetual motion simulation in the form of a beachball that never stops spinning.
I have a very convenient Incase slip which I carry my Mac around in. As well as providing protection against collisions with the books, ipods, piles of paper, alien foetuses etc with which it shares my rucksack, the foam padding of the case is an excellent insulator. So occasionally when I open the case at the end of my journey, I find that instead of sleeping quietly, my Mac has been furiously spinning its CPU or disk, and is now extremely hot, and, by the sound of the fans, all spooled up and ready for take-off. This is disturbing.
It seems clear that the power management firmware should be able to stop whatever processes are running. I imagine that a sensible way to do this would be to first send a signal to all running processes telling them to STOP. This gives the processes the opportunity to perform any critical clean-up activities (like handing control of the nuclear reactor over to another machine). After a decent period, any processes which are still running are forcibly terminated. According to Wikipedia, Power Management Unit, on a MacBook Pro, the power management functions are controlled by a tiny CPU, the settings for which can sometimes become corrupted. In that case, it might be necessary or helpful to reset the PMU back to its default settings. How to do that is described in Resetting an Apple portable’s System Management Controller (SMC). The Apple article suggests this reset should only be a last resort, if the mac fails to shut down even if the power button is held down for 10 seconds. Gulp. The Wikipedia article suggests it might be something to try if your Mac’s power management is getting funky.