Error 1601 refers to an issue with the iTunes software on your computer. See this Apple Knowledge Base article for details and recommended solution:
http://support.apple.com/kb/TA38633?viewlocale=en_US
Also, if you are on a Windows machine, have you changed/added/upgraded any antivirus programs? They can interfere with communication between the iPod and iTunes. Try to disable any auto-scan features, at least temporarily.