I don't want to scare you or anything, but there has been a line-up from Seagate that is known for those clicking problems. People complained a lot about that etc.
I bought some time ago (maybe a year) a 1.5TB Seagate Barracuda and after a day similar problem occurred, except it was more of a simple clicking than click of a mouse (like the clicking from pressing a mouse button, but not releasing). Anyways, it was going on like that for two more days and it definetely wasn't the sound of hard disk access as it was as loud as normal mouse clicking, so I thought I'd give it a go with hard scan tools. After that I found out 4 bad sectors, physical bad sectors and I'm not sure how more could I get of those before Hard Drive would fail (as compared to those that are made from electro magnetic "anomaly", there was only a limited supply of sectors to replace physical bad sectors).
Anyways, I fixed the problem three days after that. Problem was that my case was side down (for cooling), so my hard drive wasn't set on it's bottom but on it's side. As soon as I turned the case to sit up normally clicking noise stopped. And since I didn't have a single problem with it.
Never had that problem with any other hard drive, but yeah. Thought I'd shout out. Regards.
Also as someone previously said, test it with SeaTools (can get it from their official site).
Edited by Goran H. - 4/7/12 at 7:20pm