Symptom
The computer stops responding ("freezes") if it goes to sleep with an iPod connected to it.
Solution
-  Restart the computer (if necessary).
 -  Do not put the computer to sleep when the iPod is connected.
 -  Turn off sleep in the Energy Saver control panel (Mac OS 9) or the Energy Saver pane of System Preferences (Mac OS X).
 
Reset iPod. See technical document 61705, "
iPod: How to Reset" for steps to reset your iPod. 
Note: When you reset iPod all your music and data files are saved. Some customized settings may be lost.