I have a similar problem - I've used "presenter mode" in PowerPoint several
times, and change the my display settings to allow the slides to extend to a
second monitor (projector).

Once I'm done with the presentation, I'm unable to get out of the presenter
mode.  I've changed the display settings and even rebooted, but unless I
actually disconnect the external display connection and then reboot, it stays
in the mode.

This causes a big problem when I'm in the middle of a presentation and want
to switch to another program for display.

Any suggestions?  Will the add-in mentioned in the previous reply help this
problem?

Thanks