I have a 1.5 year old G4 PowerBook (1.5ghz, 512mb ram, running 10.4.8) that has been going to sleep randomly. The screen will turn black even while I am using the mouse or typing on the keyboard and then it goes to sleep and the light pulses. Yes, I have checked my power settings, and the computer is set to never go to sleep. I cannot figure out what is causing this to happen. At first I though it might be a heat issue, but I don't think thats the case since it goes to sleep rather than shutting down completely and the computer does not feel warmer than usual. If anyone has any experience or thoughts on this issue, I would greatly appreciate any advice, thanks.