...when I attempt to save a VPS file as an mpeg
First, I assume by VPS you mean a VSP project file. As you possibly know, a VSP file is not a video file and contains no video. It is merely a small text file which tells the programs what video clips are in a project, where they are stored, and what editing has been done to them.
So what exactly do you mean when you say you are trying to "save" such a file as an mpeg? Normally, you have to render a project in order to get a new video file: Share > Create Video File. Is this what you mean by 'saving'? If not, can you describe in detail exactly what steps you take...
It would also be extremely useful to know the properties of the original video in the project.