Here are the map view warning messages and what to do about them:
Menu has empty drop zones.
Double-click the menu icon to go to the menu in question. Click the Drop Zone button (shown below) to open the drop zone editor. Fill all empty drop zones by dragging images or movies to them from the Media pane.
Slideshow is empty.
Double-click the slideshow icon to open the slideshow editor. Drag photos or movies to the slideshow editor, and use the controls to set slide duration, add a soundtrack and a transition, and so on.
If you do not want to keep the slideshow, select the slideshow icon in map view and press Delete.
Movie path not yet defined.
This warning indicates there is a button that is supposed to link to a movie but doesn’t. To link a movie to the button, double-click the icon for the menu that contains the broken button (the blue menu icon that connects to the movie icon in map view). On the menu, a yield warning appears next to the broken button. Click the Media button, and then click the Movies button. Drag a movie to the button on the menu. The warning icon disappears, indicating that the button is fixed.
If you do not want to add a movie to the broken button, select the icon with the warning message and press Delete. This deletes the broken button from its menu.
Menu contains no buttons.
This problem can occur when you have added a button for a submenu to another menu in your project but have not added any buttons or content to it. To resolve the problem, double-click the icon for the menu in question, which opens the menu. Then drag a movie to the menu, add a button for a slideshow (which you must create by opening the slideshow editor and adding photos to it), and so on.
If you do not want to keep the problem menu, click its icon in map view and press Delete.
Menu has too many buttons.
This problem occurs when you have added more buttons to a menu than the theme accommodates. (When you add too many buttons, a dialog appears that allows you to add the extra buttons temporarily, but you can’t burn your project until you resolve the problem.) You must remove buttons from the menu until it has no more than the theme allows (usually 6 or 12).
Menus exceed 15 minutes.
This warning indicates that the duration of all motion elements on all of the menus in your project—including video clips in menu backgrounds, drop zones, and buttons—exceeds 15 minutes. You must shorten the video, or remove it, in order to burn your project. To shorten a video clip, you must do so in the program it was made in, such as iMovie or Final Cut Pro. Then you can add the shorter movie back into your project.