When you defrag your computer you can hear the hard drive running as it changes files back and forth. At times I can hear the same sound (or similar) but have no clue what it can possibly be doing. My 1st instinct is to unplug my internet connection should someone be hacking in my PC and using my resources. But after doing so I can still hear it working hard, on and on, and on at times. So I do a Ctrl+Alt+Del to see what is using most of my memory. Often its Firefox and Skype but even after closing both and doing nothing (hand away from keyboard and mouse) I can still hear it at work. I do not have any automatic updates for any of my software so it can't be that. I was wondering if there is some way, software perhaps, to find out exactly what it is that is making my computer do such a thing?