If your hard drive is more than 2 Gigs don't use defrag. Mine is 8 Gigs and defrag takes 6 hours. I only did it once and had to replace my hard drive a couple months later. I am guessing that defrag caused too much wear & tear in a short time. Not surprising either given all the whirring & clicking noises.

If you want to make sure that all the programs on your hard drive occupy the smallest volume the fastest way to do it is to format you hard drive (erase everything) and reinstall all the software. It might take a couple hours at most, and would stack all the programs together like bricks, one on top of another, with the maximum free space left afterward. It might also fix that problem with the sound since you would also reinstall sound card & peripherals drivers.

I don't know if you still want to defrag or would rather reinstall, so I'll keep my explanations short.