If I'm reading a web page for a while, when I go to do something I can hear a very very faint whirr preceded by an even fainter click. Obviously something has gone to sleep and woken up. Is this the hard drive starting to spin. If it is how does this work, does it need to be spinning all the time in order to react quickly. The reason I ask is to know whether my engergy saver setting are doing more harm than good. I've got the screen and computer to sleep after 10 minutes. But there is no separate setting for the HD. When I hear the click and whirr, the computer has not been asleep, but just inactive. I hope I've explained this well.