I swapped my original HDD from my late 2008 macbook unibody with a larger WD one. Any one I kept the old one for backs up every few months. I got it out today and connected it to the computer. The HDD partition would show up, I can click it and see whats inside it but soon it will eject itself and ask me for a password . I have a master password that I use, so I did use it but it didn't work. I can hear snapping sounds in the HDD. It clicks. Any one know what this might be? I have doubts the HDD died because it only has been in use about 3 years and then hardly used for backups. It worked flawless last time I used it. I do not recall dropping it or anything like that.