No, I am not trying to run a .WMV simultaneously. I have created a menu using a still from the film as a background and then simply typed up some words and converted them to buttons.
You mentioned standardising the footage, sorry how can I ensure that they are all the same?
I'm only using two clips, both from the same Premiere project. One being the film in it's entirety and then other being a 30 second trailer.
My other components are a blank PAL menu layer and a still from the film, (captured with TopazMoment).
Here's a brief list of what occurred prior to these DVD issues.
1) The editor and I put together our film.
2) We exported the movie as an .AVI file
3) I copied the file onto a data DVD
4) I brought the DVD home and ripped the file onto my computer
5) I imported the entire film back into Premiere Pro 1.5 and cut it into two pieces; Film and Trailer
6) I then exported these two parts seperately into .AVI files
7) I imported the two clips as assets and attempted to construct a DVD

Upon attempting to preview, I got the error message
I would have thought, seeing as Encore and Premiere are both Adobe programs, that this would be a simple affair. Apparently not. :(