With the DVB file loaded, you can go to VBA Editor, click menu "Tools->References...", then in the "References" dialog, see if "Microsoft Visual Basic for Application Extensibility 5.x" is one the checked references. If yes, the VBA project may have code that does some kind of changes to the VBA project, such as adding/changing references "dynamically" (which is really a bad thing to do and does not make much sense, but I do see this from time to time) either when the DVB file is loaded, or VBA macro starts.
If that is the case, to getting rid of the "saving" prompt, you have to remove the reference to the "VBA Extensibility 5.x" (and risk the VBA project being broken, unless you do some code fix after removing the Extensibility 5.X).
