Error convertoring HTML to XHTML: System.ArgumentException: The empty string '' is not a valid name. at System.Xml.XmlTextWriter.ValidateName(String name, Boolean NCName) at System.Xml.XmlTextWriter.InternalWriteProcessingInstruction(String name, String text) at System.Xml.XmlTextWriter.WriteProcessingInstruction(String name, String text) at System.Xml.XmlWriter.WriteNode(XmlReader reader, Boolean defattr) at FreeTextBoxControls.Support.Formatter.HtmlToXhtml(String input)