First are you saying that you're wanting to import DVD MF7 Project Files into VS X4? This can not happen as DVD MF7 uses *dwz as the project file format, while VS uses VSP files. Also DVD MF7 was out wayyyy before VS X4 was even thought of, let alone developed. In fact you can not use VS X4 project files (VSP) in DVD MF7.
Now since DVD MF7 is a DVD authoring program and not an editor, the only way you could use a file from DVD MF7, is if you use the Fast Export function, which is just used to export to MPEG-2. Then you could insert the MPEG-2 video file into VS. This would not be necessary, and in fact ridiculous because you would already have the video file on your system.
I think there's really nothing wrong with your VS X4, it's just understanding how each program is designed to work. You're trying to put the cart before the horse.