Hi Wim,
Thanks for getting back to me so quick

I'm using Powerpoint 2010; version 15.0.4760.1000.
The Design mode seems to work fine.
When I click on Presentation mode, it flicks to full screen, shows the first page for a split second and then the screen turns black. The navigation arrows are still showing but do not respond. The presentation crashes and won't close unless I force it with task manager.
Thanks again.