Unable to Validate File

WARNING: Parsing Error: EntityRef: expecting ';', line 1400, column 84
ERROR: Unable to parse the XML document: INPUT
 INPUT: Line 1400: EntityRef: expecting ';'
 INPUT: Line 1400: EntityRef: expecting ';'
 INPUT: Line 1400: EntityRef: expecting ';'
 INPUT: Line 1400: EntityRef: expecting ';'
 INPUT: Line 1400: EntityRef: expecting ';'
 INPUT: Line 1400: EntityRef: expecting ';'
 INPUT: Line 1400: EntityRef: expecting ';'
 INPUT: Line 1400: EntityRef: expecting ';'
Using XML_LIBRARY=/home/www/tools.ietf.org/toolsINPUT2rfc/web/public/rfc/biINPUT:/home/www/tools.ietf.org/toolsINPUT2rfc/web/public/rfc/biINPUT2:/home/www/tools.ietf.org/toolsINPUT2rfc/web/public/rfc/biINPUT3:/home/www/tools.ietf.org/toolsINPUT2rfc/web/public/rfc/biINPUT4:/home/www/tools.ietf.org/toolsINPUT2rfc/web/public/rfc/biINPUT5:/home/www/tools.ietf.org/toolsINPUT2rfc/web/public/rfc/biINPUT6:/home/www/tools.ietf.org/toolsINPUT2rfc/web/public/rfc/biINPUT7:/home/www/tools.ietf.org/toolsINPUT2rfc/web/public/rfc/biINPUT8
Parsing file INPUT
Resolving entity... http:/INPUT2rfc.tools.ietf.org/authoring/rfc2629.dtd
Resolving entity... http:/INPUT2rfc.tools.ietf.org/authoring/rfc2629-xhtml.ent
Resolving entity... http:/INPUT2rfc.tools.ietf.org/authoring/rfc2629-other.ent
Resolving entity... http:/INPUT2rfc.tools.ietf.org/authoring/rfc2629.dtd
Resolving entity... http:/INPUT2rfc.tools.ietf.org/authoring/rfc2629-xhtml.ent
Resolving entity... http:/INPUT2rfc.tools.ietf.org/authoring/rfc2629-other.ent

Apache/2.2.22 (Debian) Server at xml2rfc.tools.ietf.org Port 443
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