In this situation, once iMovie HD creates a Magic iMovie, the computer switches applications to iDVD, but because you already have an iDVD project open, iDVD won't create a new project for your Magic iMovie content. Instead, you may receive an alert such as this:
It doesn't matter if you select Yes or No; your Magic iMovie DVD project will not be created as expected. Instead, iDVD opens a new blank project.
If this happens to you:
To avoid this issue, make sure that you close all iDVD projects before starting a new Magic iMovie.