I got my MBP the other day, which has a 200GB 7200rpm HD. The HD makes a sort of clunking sound every 30 seconds or so, which doesn't seem to correlate with anything I'm doing at the time. Sometimes, my mouse will freeze for a second just after the clunk sound as well. This happens either on Power or Battery, and "Put Hard Disk to sleep when possible" isn't checked. Can anyone help?