This error usually occurs when ServiceLedger cannot create an XML parser to process internal commands. The XML parser ServiceLedger uses is provided by Microsoft Internet Explorer. Depending on your system configuration, it may be necessary to update to the latest version of Internet Explorer in order to run ServiceLedger successfully.
You can check the version of Internet Explorer by choosing 'About Internet Explorer' from its Help menu. If the version of Internet Explorer on the machine is less than 6.0, please install the latest version either via Windows Update or from Microsoft's web site at http://www.microsoft.com/windows/ie/default.mspx.
If you find that Internet Explorer is in fact 6.0 or above, be sure you are running ServiceLedger 18.104.22.168 or above.