I have heard this twice now, the first time I wasnt to sure that it was the drive; it has just happened again. I know now that it is. Its a short bzzzzzz sound which is quite loud. I think it could be serious, my mac works fine though. If i need to change the drive and swap all the contents on to another drive, I would not have a clue how to do this, any tutorials on this? Any help would be greatly appreciated!