"An error occurred while trying to replace the attachment"

I get the above message erytime Endnote tries to Sync. Has anyone else had this message? I’m not sure what the attachment is, or how to rectify this. Any suggestions would be hreatly appreciated! Thanks. 

For this error too, I would suggest calling tech support (http://endnote.com/support)) and reporting back.  doesn’t seem that any of us know.