I have that "Put the hard disk to sleep when possible" box checked under the energy saver tab, which is supposed to spin down the disk when the computer is idle to save power and to slow wear on the hard disk. However, i've noticed that when it spins down, it just spins right back up again within a minute or two! So all throughout the night, the hard disk is just constantly spinning down and up again, at intervals of 5 minutes or so. I don't see the point of this, and I believe its even more harmful than just letting the disk spin all night long. Obviously, OS X is reading/writing something when the computer is idle which is waking the drive up, but I don't have any apps open. It just seems useless to me to have this feature when it doesn't actually work like its supposed to. Does anyone else have this problem? Or perhaps a fix?