I've been having problems booting my a Dual 2 GHz Power Mac G5 (rev A) running 10.4.11. I press the power button (either on the computer itself or on my cinema display). I hear the normal rev-ing startup noise, feel/hear the fans blowing at a normal rate, and then nothing. No lights (either on the computer or monitor), video activity, startup chime, etc. If I hold down the power button to force it to shutdown and then restart, it always starts up fine. This only happens on a cold start, when I turn on my computer in the morning, after it has been turned off for more than a couple hours. This started happening in December. I reset the VRAM and PRAM. Repaired my startup disk. Ran the Apple Hardware Test. Removed an extra PCI-X card. Nothing helped. Finally, I reset the Cuda/PMU (http://docs.info.apple.com/article.html?artnum=86760), and it started behaving normally again for about a month. And then, this week, it started happening again. Anybody have any ideas on what the problem might be? Is my computer dying a slow death?