When the SWF movie with your book is loaded onto an HTML page, its "location" changes. Its URL is now the URL of your HTML page. Therefore, if you use relative paths for page files, remember that these paths must be correct relative to the HTML page and not relative to the SWF file. A similar problem arises when your HTML file and the SWF file with the book are in different folders. Then you need to either place them in one folder or use absolute paths or detail relative paths relative to the HTML file.