Look in this doc:

http://kb2.adobe.com/cps/405/kb405835.html

It says:

Solution 2: Disable the "Maintain synchronization information" setting.

Do these steps if you are experiencing widespread synchronization problems.

Note: Dreamweaver will re-create the synchronization information for your site.

1. Choose Site > Manage Sites, select the site you want to edit, and click Edit.
2. On the Advanced tab of the Site Definition dialog box, choose Remote Info and "Maintain synchronization information".
   
   Note: This will delete the existing dwsync.xml files.
3. Close Dreamweaver.
4. Verify that all of the dwsync.xml files have been deleted from your local root folder and all of its subfolders.
   
   Note: The dwsync.xml files are located in the _notes folder which are hidden by default in Dreamweaver, so check for the _notes folders and dwsync.xml files in the Windows Explorer or Macintosh file browsers. The dwsync.xml files only reside locally. Dreamweaver will never upload the dwsync.xml files to the server, and there is no reason to upload them to the server.
5. Reopen Dreamweaver, choose Site > Manage Sites, and edit the same site you selected in step 1.
6. On the Advanced tab of the Site Definition dialog box, choose Remote Info and reselect "Maintain synchronization information".
   
   Note: Dreamweaver will re-create the dwsync.xml files as you transfer files to and from the server.
7. Verify that the problem is resolved.