powerbook G4 keeps turning off or going to sleep

This is my first post in this forum and I am in desperate need of some help. I have a powerbook G4 (1.67) that I bought in 2005 before I left home for college. It has worked great up until recently when all of a sudden it starts to go crazy on me. I will just randomly turn off and wont turn back on unless I reset the PMU. It will also just go to sleep at the most random times when I'm using it. I have tried everything. I even went as far as to re-install OS X Tiger. Yeah it just went to sleep on me twice. Make that three times. It doesn't seem to be running that hot so I dunno what the problem could be. I might have to go to the apple care center in Raleigh (I live in Greensboro, NC) but I cant really afford to get it worked on right now. From what I have also seen if it does come down to me having to get a new PMU I am going to have to pay $500. Does that sound right? One of you mac genius's help me please.

Have you checked your settings in System Preferences/Energy Saver?

yupp. I have it set to never sleep when plugged in.

Could it be that your battery is a goner? They do wear out.

i thought about that....So i tried to use it with no battery. It still does the same thing. As I posted earlier I have the energy saver sleep setting set to never for when its plugged in. Well I just got back from work and it was asleep and I had to press the command key over and over to get it to turn on.

I'm really curious what this could be. Reinstalling the OS didn't work... have you tried repairing disk utilities recently? Could you post pics of your energy saver panel and screensaver settings? I remember reading there can be a problem with a "crossover" of the two settings but of course, I cannot find that info at the moment.

I Know someone that that happend to and he had his logic board replaced for it to work