Three problems could prevent the main book's links from launching external documents such as the word-processing files included with many of the digital downloads:
The default software that your computer uses to open PDF files is not Adobe Acrobat or Adobe Reader. Although most software designed to open and view PDF files should be able to render the text in our digital downloads' PDF files, navigate through the files using their bookmarks and internal links, scan their contents using the software's inherent search tools, and follow Internet and email links, we incorporate some additional advanced features in our digital downloads that are specifically designed for use with Acrobat and Reader. You may download a free copy of the Adobe Reader software (version 10.0 or later is recommended) at http://get.adobe.com/reader/.
The digital download's folders or files have been renamed, or its file structure has been altered. If you suspect this is the source of the trouble, try installing the digital download again.
The digital download was installed on a Windows system using the "Mac" ZIP file instead of the "Windows" EXE file but the contents of the ZIP file were not properly extracted.