Error maybe linked with www.w3.org

[anonymous]

When tried to export to MS Word, the following text appears:

Exception: Error executing command (return code = 5): error : Operation in progress
/var/trac/ER/xslt-stylesheet/html_filtered.xslt:1: warning: failed to load external entity "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"
C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"
                                                                               ^
/var/trac/ER/xslt-stylesheet/html_filtered.xslt:77: parser error : Entity 'larr' not defined
          <li class="first"><span>&larr; <a class="prev" href="/browser/pagetodo
                                        ^
/var/trac/ER/xslt-stylesheet/html_filtered.xslt:77: parser error : Entity 'rarr' not defined
>Previous Revision</a></span></li><li><span class="missing">Next Revision &rarr;
                                                                               ^
compilation error: file /var/trac/ER/xslt-stylesheet/html_filtered.xslt line 2 element html
xsltParseStylesheetProcess : document is not a stylesheet