Its a Mac, G4, dual processor, MDD. For about three months Ive had this problem: press the power button, the light flashes briefly, goes off, Mac does not turn on. I press the button several times per hour. Finally, after about 90 minutes the Mac turns on. I reset the time and date and everything works fine. The only problem is when I click (in the Apple menu) sleep, the Mac shuts down instead. So, next day I have to play the stupid press the power button game again. Some weeks ago I called for help. A guy from Geeks-Online came by to have a look (for $140). He said it cant be the power supply, because the Mac runs perfect once it is on. He said it must be the power button. New parts for this Mac are not availlable. From Usedmac.com I found a power button and ordered it. Today I replaced the original power button with the one from Usedmac. While the Mac was open I took out the battery and reset the PMU (pressed down for at least 5 seconds, reinstalled battery). I plugged the Mac in, no change. Same old problem. Im stumped. My hard drive has many various projects so Id like to keep the Mac for a good while yet. I'm not a Mac expert, but will appreciate all suggestions. Thanks!