What do I do if I Get Compiler Error C1003: Failed to create MSXML object?
This is quite a common error and is usually caused by having the wrong version of MSXML 4 installed
If you see this error message when you try to compile then the first thing to do is to update the MSXML 4 installation. This is easy to do by downloading the latest version. The download can be accessed here
Microsoft VoicePack SDKs
The information below is provided by Jim Vile and clarifies what may be going on:
What causes ADE to stop compiling is Microsofts SDK's. If you install either the FS2002 or FS2004 SDK_ATC_Voicepack_Setup.exe it registers a older version of the MSXML.dll that takes precedence over any other MSXML.dll installed. ADE will now fail to compile.
Microsoft did not release a SDK ATC _Voicepack for FSX.