Powerpoint flicks, especially the first slide.

How do I stop powerpoint from flicking when trying to use a powerpoint show
slide show on the projector. Xp system. Both Dell machines. Projector can
run via S cable DVD fine, its just when you try to use the laptop pc that it
will not work properly. when there is a source, pushing Fn F8 does get
powerpoint up on the projector (though it is 2/3 of the screen size, and its
flicking as well as making the laptop squeek in time.
The laptop is a couple of years old, the projector new. Is there some way of
fixing this?