I just received my new Asus EeePC 1001px netbook. After installing Ubuntu 10.10 on it, I've noticed that my hard drive is making a clicking noise. Now this is not a loud clicking noise nor it's constant (only sounds occasionally and when hard disk is not writing or reading anything). Another strange thing is, this only happens when netbook is using battery power, the moment I plug in AC power clicking stops. Additionally I noticed that when I go into BIOS I can hear the click only once, same thing happens if I boot Ubuntu from USB. That led me to believe the problem is within operating system.
I did all the surface scans and SMART tests and everything seems to be fine. Now noise sounds like heads are trying to "park" themselves so I tried disabling "spin down" option in Power Management but it didn't help.