When delivering a Keynote presentation, you may experience various applications opening unexpectedly. Applications likely to open include Apple Software Update, Exposé, Front Row or any application configured to use a timed launch sequence. To avoid this behavior, disable the ability for any other application to open during a presentation, in Keynote's preferences.
- Open Keynote.
- Open the Preferences Window (Keynote > Preferences...).
- Select the Slideshow tab.
- Deselect Allow Exposé, DashBoard and others to use screen as shown in the screenshot below.