SYMPTOMS
All versions of the MSXML parser (2.0, 2.5, 2.6, 3.0, 4.0, 4.0 Service Pack 1 (SP1) and future releases) share the same COM TypeLib.
When you install MSXML 4.0 (SP1 or later), the TypeLib version information for the MSXML interfaces (such as IXMLDOMDocument, IXMLDOMNode, IXMLDOMNodeList, IXMLDOMNamedNodeMap) in the registry are updated to 4.0 (or the newer DLL).
The following is the registry information for IXMLDOMDocument interface from a computer that has MSXML 3.0 installed:
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}]
@="IXMLDOMDocument"
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}\ProxyStubClsid]
@="{00020424-0000-0000-C000-000000000046}"
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}\ProxyStubClsid32]
@="{00020424-0000-0000-C000-000000000046}"
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}\TypeLib]
@="{F5078F18-C551-11D3-89B9-0000F81FE221}"
"Version"="3.0"
After you install MSXML 4.0, the version of the TypeLib is changed to 4.0 as follows:
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}]
@="IXMLDOMDocument"
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}\ProxyStubClsid]
@="{00020424-0000-0000-C000-000000000046}"
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}\ProxyStubClsid32]
@="{00020424-0000-0000-C000-000000000046}"
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}\TypeLib]
@="{F5078F18-C551-11D3-89B9-0000F81FE221}"
"Version"="4.0"
At the same time, a new key that is related to MSXML 4.0 is added under the TypeLib of the MSXML DLL as follows:
Windows Registry Editor Version 5.00
...
[HKEY_CLASSES_ROOT\TypeLib\{F5078F18-C551-11D3-89B9-0000F81FE221}\3.0]
@="Microsoft XML, v3.0"
[HKEY_CLASSES_ROOT\TypeLib\{F5078F18-C551-11D3-89B9-0000F81FE221}\3.0\0]
[HKEY_CLASSES_ROOT\TypeLib\{F5078F18-C551-11D3-89B9-0000F81FE221}\3.0\0\win32]
@="C:\\WINDOWS\\system32\\msxml3.dll"
[HKEY_CLASSES_ROOT\TypeLib\{F5078F18-C551-11D3-89B9-0000F81FE221}\3.0\FLAGS]
@="0"
[HKEY_CLASSES_ROOT\TypeLib\{F5078F18-C551-11D3-89B9-0000F81FE221}\3.0\HELPDIR]
@="C:\\WINDOWS\\system32"
[HKEY_CLASSES_ROOT\TypeLib\{F5078F18-C551-11D3-89B9-0000F81FE221}\4.0]
@="Microsoft XML, v4.0"
[HKEY_CLASSES_ROOT\TypeLib\{F5078F18-C551-11D3-89B9-0000F81FE221}\4.0\0]
[HKEY_CLASSES_ROOT\TypeLib\{F5078F18-C551-11D3-89B9-0000F81FE221}\4.0\0\win32]
@="C:\\WINDOWS\\system32\\msxml4.dll"
[HKEY_CLASSES_ROOT\TypeLib\{F5078F18-C551-11D3-89B9-0000F81FE221}\4.0\FLAGS]
@="0"
[HKEY_CLASSES_ROOT\TypeLib\{F5078F18-C551-11D3-89B9-0000F81FE221}\4.0\HELPDIR]
@="C:\\WINDOWS\\system32"
When you remove MSXML 4.0, following key is removed:
[HKEY_CLASSES_ROOT\TypeLib\{F5078F18-C551-11D3-89B9-0000F81FE221}\4.0]
However, the TypeLib version information under each interface is not changed back to an earlier version. For example, after you remove MSXML 4.0, the version of the TypeLib of IXMLDOMDocument interface is 4.0 instead of 3.0.
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}]
@="IXMLDOMDocument"
...
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}\TypeLib]
@="{F5078F18-C551-11D3-89B9-0000F81FE221}"
"Version"="4.0"
This may cause problems in applications that use the MSXML TypeLib to do automation, or late binding, or may cause problems in any application that requires runtime interface type discovery through a TypeLib.
RESOLUTION
To resolve this problem, revert the TypeLib version information to the correct version. To do this, reinstall or reregister any version of the MSXML parser on the computer. For example, if you reinstall MSXML 3.0, the registry information changes back to 3.0.
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}]
@="IXMLDOMDocument"
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}\ProxyStubClsid]
@="{00020424-0000-0000-C000-000000000046}"
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}\ProxyStubClsid32]
@="{00020424-0000-0000-C000-000000000046}"
[HKEY_CLASSES_ROOT\Interface\{2933BF81-7B36-11D2-B20E-00C04F983E60}\TypeLib]
@="{F5078F18-C551-11D3-89B9-0000F81FE221}"
"Version"="3.0"