when it hangs and does not react. I am posting it so that I do not have to google it out again :-). Key is Menu + Select combination.

Here comes the detailed version (saved from Google Notebook):

  1. Toggle the Hold switch on and off to avoid "hold trap"
  2. Press and hold the Menu and Select buttons until the Apple logo appears, about 6 to 10 seconds. You may need to repeat this step.

Tips:

- set iPod set it on a flat surface.
- Make sure the finger pressing the Select button is not touching any part of the click wheel.
- make sure that you are pressing the Menu button toward the outside of the click wheel, and not near the center.
- if battery is dead, above may not work, try to power the iPod - to a power adapter and plug the power adapter into an electrical outlet, or connect iPod to your computer. Make sure the computer is turned on and isn't set to go to sleep.
- use only one finger from one hand to press the Center (Select) button, and one finger from the other hand to press the Menu button.

After reset iPod music and files are saved, as well as date and time but some customized settings may be lost.