Hi ,
Before proceeding with the troubleshooting, I’d suggest you to check if there is any error in your Device Manager, if any, please uninstall drivers and reinstall it again.
Here’s an Apple KB article that may just have the fix for the issue you’re facing:
iPhone or iPod is not recognized properly by computer when USB drivers are not installed properly or are out of date
http://support.apple.com/kb/TS1538
Follow the troubleshooting steps mentioned in the above article, in the order and check if your issue gets fixed.
Also don’t forget to check if the issues would be fixed in
clean boot.
If the steps mentioned in the above do not fix the issue, I’d suggest you to contact Apple Support:
Apple – Support – iPod – iTunes
http://www.apple.com/support/ipod/
