As LVTravel wrote, the problem is usually with the video hardware
and/or the driver. And the problem can usually be solved by directing
the video output exclusively to just the secondary monitor, ie blank on
your notebook.
If you are using two monitors and have two video outputs, PowerPoint
can be more powerfully used if you turn on Extended Desktop. This
effectively enlarges your Windows Desktop to cover both displays and
you can move your mouse from one to another. PowerPoint can then be
configured (Slide Show/ Set Up Show...) to Display slide show on
Monitor 2. You can do other stuff or look ahead while the PowerPoint
show is undisturbed on the secondary monitor (eg projector).
Extended Desktop can be turned on under Control Panel Display (or right
click the Desktop and select Properties) the last tab (Settings). Of
course your PC must have the proper video drivers. For Windows XP,
usually this is already in. For Windows 2000 or Windows 98, you have
have to go to your video hardware manufacturer.
