Details, please.
I assume you are referring to Windows Live Mesh.
If so, go here:
http://windowslivehelp.com/forums.aspx?productid=24
In any event, if the files that you have specified to sync are getting a new extension on the destination PC, that likely means that the files have not yet been copied over. Before the sync completes,
the temporary copy of the file is a placeholder. Once the file cmpletely transfers, it is renamed to the original.
-steve
~ Microsoft MVP Windows Live ~ Windows Live OneCare| Live Mesh|MS Security Essentials Forums Moderator ~