Okay, this just started happening to me yesterday-- When I'm listening to iTunes, every once in a while it will stop playing and go beachball on me. Happens for about 10-15 seconds then goes back to playing. During that time, my hard drive starts making a "click" sound, about once a second (different from the usual access clicks, louder). It almost sounds like the drive is skipping, and seems to me that it's having trouble reading. I've done a disk utility scan on the drive, and it reports no problems. I'm not sure how frequent the issue is, because I have enough ram that there is a lot of caching being done. Has anyone else run into this? There are no diagnosable errors in the drive, but obviously it's having trouble reading.