My iPod won't turn off

The normal way to turn off an iPod (with a Click Wheel) is to hold down the Play/Pause button for 2-3 seconds. Sometimes, the iPod may get into a state where this does not work.

Workarounds
The short-term way to fix it, hold down Center and Menu for 10 seconds to reset the iPod. You will not lose any songs or anything, this is like a 'reboot' for the iPod. After this, the iPod should turn off just fine.

Some report this symptom is defined as a hard drive fault from the 2006-1-10 Update. Which, for V4 and under versions, and possibly even Nano and Video, the hard drive will not respond to both ways of turning off, or soft reset. forcing the user to restore the iPod. or let the power run dry. The only real solution of this is to find an updater that restores your iPod to a version before the 2006-1-10 updater. (e.g. Updater 2005-6-26. Which reverts to 1.2) Currently, no possible solution is found by Apple. As Apple replies with an automatic response stating to send the iPod in for replacement.

Others report that a restore including a full update to the latest version fixes the problem, the only downside being that of course "restore" wipes all your songs and photos and you have to reload the iPod from scratch. Yet another reason to backup your iPod.