well honestly i have no idea why the secure shredder would be causing this....Is there any way you could contact your computer manufacturer (HP) and let them know about your hard drive? The computer manufacturer (HP) should still be covering you since the pc is not that old....I know Hp and have worked with them before, usually when it comes to a serious issue like this, they will help you out. I am hoping you can get a new hard drive. As for the clicking sounds you are getting, it does sound like its mechanical....
What i recommend is that you immediately backup everything, all your data, etc. That you do not want to lose, in case you hard drive completely fails. If you get another hard drive, I recommend the brand western digital. A cheaper way if you have the know how, would be to buy yourself a new hard drive and install it, or have hp fix it with the hard drive you bought. But it's up to you.