Question: When my computer is turned on but not being used, why does it sound like the harddrive is processing? 

Answer: Your operating system and other programs are still accessing your hard drive. You also need to make sure that nobody else is using it without your knowledge. If you have broadband make sure you have a Firewall installed and the permissions for it are correct, if you don't recognize it remove the permission, if you make a mistake you can always turn it back on!
This question from the Yahoo Q&A forum is categorized in the topic: Society & Culture