My ibook g4 (os x 10.3.7) is having some sleep issues - mainly, I will close the lid to put it to sleep, and then upon opening the lid, (even after just 1 minute of sleep time), it will not wake up, and it will not respond to me pushing the power button, and then all of a sudden it will have restarted itself. So i don't know if it had shut itself off, or what, but neither does it indicate that it was shut down improperly. also, have tried this in various combinations of battery charged fully, with or without ac power, and it invariably happens, regardless of power setup. Also, sometimes I will close the lid to put it to sleep and i can still hear it "working", and I think that is weird. So, I'm thinking I will reset the PMU? But does that mess with the hard drive and should I do a complete back up of my stuff first? I usually do a backup/archive by making a bootable clone on an external hd, and archive stuff to cd's. ok, thanks for your advice. and i am still under 1 year warranty of parts and labor and live by 2 apple stores, if you think it needs to be taken in for repairs.