In Word 2000/2002(XP)/2003 go to the Tools Menu and select 'EndNote > Unformat Citations' command. In Word 2007 with Endnote X or earlier, go to the Add-Ins tab and choose the 'EndNote > Unformat Citations' command. In Word 2007 with Endnote X1 or later, go to the EndNote tab and choose the 'Convert Citations and Bibliography > Convert to Unformatted Citations' command. In Word 2010/2013/2016 with Endnote X4 or later, go to the EndNote tab and choose the 'Convert Citations and Bibliography > Convert to Unformatted Citations' command. The issue could be related to document corruption.