I have this odd clicking sound on my HDD that came with my Macbook. It's a Hitachi HTS545025B9SA02. When I'm not doing anything on the Macbook, the hard drive runs fine. But when I do something, such as hit the back button constantly on my web browser or any activity really, it occasionally makes a weird sound. I am not sure how to explain it, though. I've Googled the odd clicking sounds for HDD's and all of the sounds I found were way too violent sounding. This sound coming from my HDD is very small and can only be heard in a silent room, with your ear close to the Macbook. Still, I'm trying to describe how it sounds....it almost sounds like an EXTREMELY SMALL frog croak. I'm not sure if it's just the wheel spinning...or what? Also, when it makes this odd clicking sound, it SOMETIMES freezes for about half a second, maybe a second. Thing is -- I got this from Micro Center, which is 2 hours away fro me...and I don't think I can convince my parents to drive back there again.