Hello there, podcastpapa.
It sounds like after an initial sync, you are unable to sync again without restarting your computer running Windows Vista. It's possible there may be an issue with the iPod Nano not being ejected properly from iTunes. To make sure, review the recommendations in the following Knowledge Base article:
How to eject an iPod - Apple Support
You can safely disconnect your iPod and unplug the USB cable if the iPod displays any of the messages or screens below:
- "Charging"
- "OK to disconnect"
- The iPod main menu with selections like Music, Settings, and Extras.
You can also safely disconnect your iPod shuffle when it displays a solid amber or solid green LED.
You must eject your iPod before you disconnect if it displays any of the screens below:
- "Do not disconnect"
- "Connected, Eject Before Disconnecting"
- "Sync in Progress, Please Wait ..."
You must eject your iPod shuffle first before disconnecting when it displays a blinking amber LED.
If the "Enable disk use" or "Manually manage music and videos" options are turned-on for iPod in iTunes, you will need to manually eject your iPod each time before you disconnect the cable.
- Locate your iPod.
- From the sidebar on the left-hand side of the iTunes window, click the eject icon.
After you select your iPod, you can also eject it using the Command and E keys on your keyboard.
If you find the issue persists, then feel free to go over the troubleshooting recommended in this article:
iPhone, iPad, or iPod not recognized in iTunes for Windows - Apple Support
Thanks for being a part of Apple Support Communities.
Cheers.