Can anyone help me please? I have an imac G5 running 10.4.11 and it automatically shuts down after an approximate idle hour. I haven't timed it, but it's close to an hour, a little less maybe. Is the internal battery dying? Can anyone help me figure out this annoying problem so I don't have to spend a fortune on a shop repair? Thank you in advance for any advice any of you amazingly smart people might have.