maclover6, have you tried the AppleJack utility? Recently I had some sleep/wake issues on my PM G5 that I couldn't cure via the usual suspects. In my case, when waking the display from display sleep--the CPU wasn't asleep--by moving the mouse or hitting a key, the screen would wake up, then about a second later the curtain of death would descend, and the display locked up. I had to power off the G5 and restart every time this happened--the logs show kernel panics at those times, but those may have been caused by my powering off a running machine which simply had no active display (vs. shutting it down). Anyway, I remembered I had installed AppleJack, which is a disk repair utility that also removes system disk caches; these get rebuilt automatically in the next restart. Running AppleJack cured the sleep problem on my computer (knock on aluminum). I looks to me that something had corrupted one of the system cache files on disk, and the system has now successfully rebuilt that file.
AppleJack is at: http://applejack.sourceforge.net/
After installation, restart your Mac in single-user mode <Command-S>, then at the command line type:
applejack auto restart
This will run AppleJack by iterating through all its tasks in order, then restart your computer in normal mode.