WLW: QI for IEnumVARIANT failed on the unmanaged server.

It maybe popup an error message to say that “QI for IEnumVARIANT failed on the unmanaged server” when open the Windows Live Writer.

After search on google, I found the resolution is import some settings into registry.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINESOFTWAREClassesInterface{00020404-0000-0000-C000-000000000046}]
@="IEnumVARIANT"

[HKEY_LOCAL_MACHINESOFTWAREClassesInterface{00020404-0000-0000-C000-000000000046}NumMethods]
@="7"

[HKEY_LOCAL_MACHINESOFTWAREClassesInterface{00020404-0000-0000-C000-000000000046}ProxyStubClsid]
@="{00020421-0000-0000-C000-000000000046}"

[HKEY_LOCAL_MACHINESOFTWAREClassesInterface{00020404-0000-0000-C000-000000000046}ProxyStubClsid32]
@="{00020421-0000-0000-C000-000000000046}"

You can also download the file here, unzip and import it to your registry.