This may seem strange but when I watch quicktime movies - ie .mov files, there are parts of it that make my mac make an incredibly loud noise - that is so loud (and not relevent to the volume of what's being played or the macs volume) that it makes me jump - a bit like a gun shot going off not too far away. I'ts actaully sounds almost as if someone got a hammer and swung it at the aluminium case ????? I've watched online movies and dvd movies and never had the problem with them just these quicktime ones that I've downloaded. It's also replicable - ie the one i have at the moment is about shoulder function and 1.03 the noise occurs Does anyone have any clue what it might me or if it's dangerous???