Error parsing XML document

/mnt/stor/prosjekt/menota/public_html/guidelines/index.page:106: parser error : Entity 'nbsp' not defined
           <p>&nbsp;</p>
                    ^
/mnt/stor/prosjekt/menota/public_html/guidelines/index.page:126: parser error : Entity 'nbsp' not defined
<p>&nbsp;</p>
         ^
 at /usr/lib/perl5/site_perl/Aksis/XSLTransformer/Application.pm line 154