Error message

• Warning: Cannot modify header information - headers already sent by (output started at /var/www/asansw/includes/bootstrap.inc:1692) in drupal_send_headers() (line 1551 of /var/www/asansw/includes/bootstrap.inc).
• Error: Call to undefined function xml_parser_create() in drupal_xml_parser_create() (line 219 of /var/www/asansw/includes/unicode.inc).