HDD in my desktop PC stops spinning randomly - every few minutes. OS - Ubuntu 12. This not causes total system hang, but when I perform any action, it waits until HDD will "wake up", usually about 30 seconds or more. I can hear how it stops and starts spinning. Looks like some power saving mode in laptops, but very long delay until HDD decides to start working again.
Possibly, issue appeared after last system updates - a few days ago HDD worked ok.