Sync Services error on Windows 7 when iPhone 4S is plugged in I am currently running iTunes 10.5.1 on a Windows 7 Home PC and when I plug my iPhone 4S into my computer via the USB cable it freezes. iTunes in Task Manager shows up as not responding and after a few minutes it displays the following error:


  iTunes was unable to load data class information from Sync Services.
  Reconnect or try again later.


What causes this issue and how can I resolve it?
I googled your error message and I found this page and this apple support thread.

Hope this helps ! 

Edit:  Solution #2 in the Lei Mobile site seemed to resolve my issue.  I renamed the C:\Users\username\AppData\Roaming\AppleComputer\SyncSerivces to SyncServices_old.  I was at least able to plug in my iPhone and perform an initial back up.  

I will continue to use to see if that is the permanent fix.