This problem may be caused by a conflicting script on the page, or may be caused by not having at least one menu item assigned to the Main Menu category.
In some cases the issue may show in certain browsers. This is usually a script conflict. If the menu does not show in any browsers, then it is more likely a navigation menu setting issue.
Navigation Menu Settings
If the navigation menu is not appearing at all, the most likely cause is that you do not have at least one menu item assigned to the Main Menu category. Another possible cause could be a special character in one of your menu item name.
The most common cause for this, is the use of the Showcase Listings slideshow feature on the home page. The DeluxeMenu may not work on the home page, but works on all other pages that do not have the slide show.
Try disabling the slide show or use a different Showcase Listings format. If there is another script causing the problem, you may want to try removing it, or have LinkUSystems, Inc. remove it for you.