Thanks for the replies.
The machine is clean inside and if I reverted back to 10.4.2 I would not experience any sort of shutting down. But, I want to move forward.
I will pay attention to the log. There is absolutely no indication of any sort when it shuts off, no fans, no errors, no...
I have a 2005 PPC Dual 2.3 with 2.5 megs of ram which has been very stable running 10.4.2. I upgraded to 10.4.10 about 2 years ago and experienced constant shut-downs of my computer with no warning. Maybe 5-6 times a day. Nothing reproduceable.
I reverted back to 10.4.2 and everything was...