Well both of the 500GB ones I have are doing it, and they are 2 different models.
Yea if I don't touch it, they will spin down and the light will go off, but they are still running even tho the light goes off and you THINK they are off.
it will spin down on it's own, or you can hit the power button and shut the drive down. and when you do, The computer no longer see's it. and the light on the Ext drive turns off.. but yesterday I felt it 5 hours later, and it's still a little warm, and still spinning. So I went into the other room, and the other one is doing the same thing. So basically I think as long as it's plugged in. it will keep spinning. that's what mine are doing at least.
not sure what to think. the one plugged into MY computer has not been powered up in over 2 weeks, yet it's still spinning and wont stop unless I unplug power.. weird huh.