Site navigation drop-down menus are expanding under my rich media.

This is most likely a z-index conflict between the site navigation drop-down menus and the ad units.

The z-index of Studio units is set by default at between 999999 and 1000000 to ensure that units expand over the site content. If the site drop-down menus have a z-index less than 999999, the menus will expand under the ad units.

Let's troubleshoot. First question.