I have an Intel Core Duo iMac, and just recently it started making a sort of "chirping" sound. It's really the best way to describe it. It seems to only do it though when I'm writing to an external hard drive, which seems very odd to me. I've backed up my entire system just in case it's a precursor to something worse. But does anyone know what might be up? It's never done this before. It also never did this when I was running 10.4.8 or below, just when I updated to 10.4.9. I don't know if that has anything to do with it or not though.