Problem = Object reference not set to an instance of an object or Retrieving the COM class factory for component with CLSID {DC0C2640-1415-4644-875C-6F4D769839BA} failed due to the following error: 80040154.

Solution = This is the most common problem that could occur when you run SyncTunes. This occurs because SyncTunes was unable to to find iTunes on your PC. If you are sure that iTunes is installed, then the error is most likely to occur because iTunes installation is corrupt on your system. You can uninstall iTunes and reinstall it to fix the problem and the run SyncTunes again from your SD card.

 Problem = Retrieving the COM class factory for component with CLSID {DC0C2640-1415-4644-875C-6F4D769839BA} failed due to the following error: 80080005.
or Retrieving the COM class factory for component with CLSID {DC0C2640-1415-4644-875C-6F4D769839BA} failed due to the following error: 800702e4.

This problem occurs if iTunes is being run as a different user than SyncTunes, this causes communication problems in two programs (Remember that starting in Windows Vista, you can run applications as an Administrator, which is like being a different user)

The error can be avoided by making sure you start both SyncTunes and iTunes with the same user credentials.
Make sure iTunes is not running when you start SyncTunes. Start SyncTunes and it will automatically start iTunes. Since iTunes is started by SyncTunes it will have the same user credientials.
Another way to resolve this problem is to go to Run and type dcomcnfg and hit enter. This will bring up the component servces snap-in. Select computers, My Computer and then DCOM Config. Find the iTunes icon under the DCOM Config. Right-click on the iTunes icon and select the Properties context menu option. This will bring up a dialog box. Select the Identity tab. On the Identity tab select the radio button named “The interactive user” and click Ok.

Problem = Could not load file or assembly ‘Interop.iTunesLib, Version=1.11.0.0, Culture=neutral, PublicKeyToken=null’ or one of its dependencies. The system cannot find the file specified.

Solution = Do not copy SyncTunes.exe from SD card to elsewhere on your PC. You have to run it from your SD card only. Otherwise the program will not work.  If you are running from removable storage of your phone and still getting the same error this means some files from your SD card are deleted. Disconnect any usb connections beetween phone and PC. Open the app from phone and install on SD card again.

Problem = Creating an instance of the COM component with CLSID {DC0C2640-1415-4644-875C-6F4D769839BA} from the IClassFactory failed due to the following error: 80010108.

Solution = This error might occur if you are using iTunes while SyncTunes is in the process of Syncing. Close iTunes then run SyncTunes.exe it will automatically start iTunes. Select your playlists to sync and while the Sync Tunes is syncing, do not use or close iTunes until the Sync Tunes is finished syncing.