I admit I did not read all the responses, however from playing with and tearing up dozens of computers over the years I offer this advice. If the fixes listed above do not work then I would be afraid the hard drive was about to go out. It has been my experience with clicking noises from the HD (loud, not the usual noise you get from accessing data) is an ominous sign and either the HD has gone out or is about to. It shouldn't sound any different from the 120 GB HD. I would take it back, which I think you said you did but this is for others who may be having the same problem.