I'm totally dumbfounded by this. Once again after having my iBook back for 2 weeks the fan did it's thing again. Not as loudly this time but it stayed on for over an hour so I call Apple. This time they had me 'reset-all' in the Firmware settings, then run the hardware check disk. They gave me a case # and said call if it does it again. He wanted to know if I had it on a flat surface....which I do but I also had put four 3/4" black rubber feet under it so it would have a little better cleance so it wouldn't overheat...wishful thinking on my part, I suppose. The dang thing got so hot in the HD area that it melted some of the black onto the bottom of the iBook! It'll come off...but still, that's pretty dang hot, don't you think? Fran