If you attach a Word document, Excel spreadsheet, or PowerPoint presentation to your Presenter '09 presentation that's in a Microsoft Office 2007 / 2010 file format (DOCX, XLSX, PPTX), you may find that it has been changed to a zip file in your published course.
This typically means that your hosting server does not have a MIME type for these newer file formats. As a result, it treats them like zip files.
Here are two options for correcting this issue:
Ask your server administrator or hosting service to add DOCX, XLSX, and PPTX as MIME types to the server.
Or, save the affected file in a backwards compatible format (DOC, XLS, or PPT). Then reattach it to your presentation, and republish.