When an iPod is configured to synchronize with a Mac computer, the Mac formats the hard drive or flash memory in the iPod using the HFS file system. This file system is incompatible with Windows, making a Mac-formatted iPod unusable on a Windows-based PC. If you have a Mac-formatted iPod you want to sync with a Windows PC, you can use iTunes to return the iPod to its original factory state and format the internal storage for use with Windows. Warnings Writer Bio

How to Format an iPod From Mac to Windows  3 Steps  - 2