That DLL is part of Microsoft's XML Core Services 4.0. There's version 6 of this DLL -- MSXML6, but it doesn't support everything that version 4 did. Check if your version is MSXML4.dll SP3.
description-of-an-update-for-microsoft-xml-core-services-4-0-service-pack-2-171a0bd5-cb42-8d6a-5d43-08df0d54e23c
ms06-071-security-update-for-microsoft-xml-core-services-4-0-134d3572-d605-89e8-d967-45327a1f846a