If you’re having Zune syncing problems, the first thing you’ll probably try is to uninstall and reinstall the Zune Software on your PC. Unfortunately, this may not solve the problem since the uninstaller software will miss certain installed DLL files, and will not clean up the registry file on your PC system. So what can you do?
Fortunately, someone has developed a program called UnZoone which will clean up all of these straggler DLLs and registry entries that are associated with the Zune Software. Using UnZoone will help you initiate a clean removal of the Zune Software, after which you can do a reinstall which should help resolve any syncing issues.
You can get UnZoone from this link.