<!DOCTYPE xml PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
Then your parser may connect to w3.org for validation. If w3 blocks you for hammering their server, then you may get this error message: http error : Operation in progress
http error : Operation in progress
If you don't want/need validation against the DTD (and you probably don't), you can turn off that feature in XML::LibXML:1.70
$parser = XML::LibXML->new(load_ext_dtd => 0);
< 1.70
$parser = XML::LibXML->new();
$parser->load_ext_dtd(0);