My aging G4 Quicksilver is still very operable yet have had mysterious problems with mouse tracking, USB ports not being recognized and now the machine wants to shut off after being asleep for some time. Someone suggested that it could be a voltage regulation problem, but service personnel have not been able to duplicate the problem with a bench test. In short, when I have a startup problem (the startup button will start to glow, at startup and then the light goes out and the machine fails to boot) or if I find the machine turned off after I left it to sleep at night or a few hours during the day, I will open the case and shut it. This little nudge seems to be a temperary fix. Nervous it does make me that my time is short with this trusty box. any ideas?