I've run into this problem a lot.
Sometimes Designer tries to be helpful and tries to determine where you might want a page break to occur. This can sometimes result in these "ghost" pages that don't appear in the design view but show up in the final PDF.
To remove the "ghost" page, switch to the xml view and search for the word "break". I don't remember the exact tag name, but you'll see the page name mentioned in the tag attributes.
Remove the entire tag and your "ghost" page should be no more.