There are many ways to create navigation menus, and there are just as many wrong ways as right ways. When building your navigation you need to be sure the search engines are able to read and follow all your links. If there are no navigable links for the search engine to follow they’ll assume you have a one-page site and move on.
This post is part of a continuing series on the topic of:
Optimizing for Maximum Search Engine Performance
Sub-Topic: Search Friendly Elements.