Error parsing XML document

/mnt/stor/prosjekt/menota/public_html/guidelines-2/contents/contents_2-0.page:135: parser error : Entity 'nbsp' not defined
<p>&nbsp;</p>			
         ^
/mnt/stor/prosjekt/menota/public_html/guidelines-2/contents/contents_2-0.page:140: parser error : Entity 'nbsp' not defined
<p>&nbsp;</p>
         ^
 at /usr/lib/perl5/site_perl/Aksis/XSLTransformer/Application.pm line 154