Problem: You can't get PP to go to Slideshow mode, that is go to full screen to show the presentation.

Solution: A possible cause is if your display is setup for dual monitor view. In that case, the presentation will 'show' on the nonexistent second monitor. In Powerpoint, go to Slide Show > Set Up Show. Under 'show on' select primary monitor and then close PowerPoint. Right click on your desktop, choose properties, then settings, and click on the monitor symbol number 2, then uncheck 'extend the desktop to this monitor'. Now open PowerPoint and open your presentation and select View > Slide Show. It should work now.