I noticed today that the hard disk on my new iMac is making an annoying hummm. It's a 500GB WD5000AAKS-40TMA0 drive. I know it is the disk since if I keep the iMac idle long enough for the disk to spin down it disappears. Holding the case of the iMac do not get rid of the noise. If those disks were not so hard to access ... I don't feel like sending back the machine since everything else seems ok (no dead pixel etc ). Anyone with a suggestion or having the same problem?