Hello, I have one of those 400 gig d2 Big Disk Extremes via firewire 400 to my mac mini. I've noticed that very frequently on idle (i.e. when im not doing anything on the computer or when no apps are actively running e.g. like a movie on Quicktime) the HD decides to make a strange churning noise. Its a different kind of sound to hard drive seek or write. Strange thing is when it becomes active from idle i.e. when I load an app up the sound stops? Do I have rats in there?