I just updated the firmware of my popcorn hour, and the annoying ‘harddisk never stops spinning’ bug popped up again. The media center is in the living room, and having a whirring disk there is annoying. So I started to find a solution, posting on the NMT forum, finding only that there is none. To find the solution, I logged in using telnet and started shooting off processes. In those tries, I found out a few that made the problem less, but not go away. Then, I rebooted and guess what? It spinned down and was quiet.
I gave up on understanding what was going on, but I’m happy that the problem seems fixed now.