It's not a stupid question. It's just that traditional mechanical hard drives only have a life-span of about 5 years. Aside from wear and tear, sectors can become bad and eventually the arm inside of the hard-drive that reads the disk starts to skip sectors and hits the disk which produces the clicking noise. You should always try to backup your data if you hear the noise and then put in a new h/d, because it means you're going to lose your data. They're making solid-state hard-drives (like flash drives) now to use as your hard-drive because it won't have this problem and will be faster, etc..