M4600 makes odd sounds under Ubuntu 11.10

It's like the "click" sound of hdd failure and happens every 15 minutes or so. I have Ubuntu 11.10 installed on a 80 gb 2.5 " external hdd but the sound comes from inside the laptop clearly, there is nothing wrong with the external unit so far. I don't know what it is, no further symptoms occur appart from the strange sound but I'm afraid something may be broken.It only happens when I'm using Ubuntu , but not with Windows 7. Before this I had problems with the graphics fan that dissapeared spontaneously, I don't know if both things are related. What puzzles me most is that the "click" sound only happens under Ubuntu.

 

I cannot give you a definitive answer. Today's operating systems do various stuff without asking user what he thinks about it. I have similar "problem" with my external drive (but I think your internal HDD, since it is not used permanently under Ubuntu, is treated like my external); my external disk is configured to turn off when it is not being used for 15 minutes or so; I can spent entire evening not using it, but every now and then it activates itself though I haven't requested anything from it. I assume my OS is requesting something from that disk without me knowing about it. I don't know exactly, what is the nature of your problem, but I think it could be the same as mine - OS i turning internal disk on and off.