Peter, Have you checked the PRAM battery? If it's below 3.2V (I think I saw this value in a repair manual from Apple), you need to replace it. Check it in-place, it won't register the loaded volts otherwise. I remember there were a lot of strange and unsolvable problems with older Macs that had a weak or dead PRAM battery. I would imagine more modern units are susceptable to the same stuff. Also, I have an 8500/150, which I got with the Apple upgrade to 604e/200 MHz already installed. It refuses to stay shutdown if the room temp is above eighty some-odd degrees F.(80° F = 26.7° C) So, I have to stand ready at the power switch and shut it off as soon as it chimes... I'm still not sure what that problem is, but this list is for G4s, not 604es. Hope this helps... -- D V drteknik at earthlink.net "All change is not growth, as all movement is not forward." -- Ellen Glasgow