The synchronization should be set up only on the one computer. If you have the xml connection set up on more computers you should immediately disable the unnecessary connection.
The synchronization can be disabled by entering Manage--> Online Portals---> and choosing the proper xml plugin from the menu on the left.
Next you should unmark the box titled" Uncheck this box to disable this plug-in"
If you want to enable the synchronization on a given computer then the box " Uncheck this box to disable this plug-in" should be marked