Error convertoring HTML to XHTML: System.Exceptio

Error convertoring HTML to XHTML: System.Exception: Unexpected EOF parsing start tag 'img'
at FreeTextBoxControls.Support.Sgml.Entity.Error(String msg, String arg)
at FreeTextBoxControls.Support.Sgml.SgmlReader.ParseStartTag(Char ch)
at FreeTextBoxControls.Support.Sgml.SgmlReader.ParseTag(Char ch)
at FreeTextBoxControls.Support.Sgml.SgmlReader.Read()
at System.Xml.XmlWriter.WriteNode(XmlReader reader, Boolean defattr)
at FreeTextBoxControls.Support.Formatter.HtmlToXhtml(String input)