I've got an iBook G4, running version 10.4.7. Never had any problems with it. Yesterday I left for class and forgot to plug my charger in. By the time I got back the battery was dead and it was in its safety mode. No big deal there, but then today I shut the lid before heading off to class and came back to it shutdown instead of asleep. This happened twice. Is this something I should get checked out, or is there anything I can do to fix it?