The auto pan/zoom or movement of slides can be turned off from the spanner icon 'slideshow options' button. This is located just above the storyboard in the main PhotoVidShow screen. Select this then un-tick 'enable pan/zoom on slideshow'.
Also you can turn off or adjust the pan/zoom on an individual slide basis. Left click a slide, then select the pan/zoom tab on the left. This tab option will only be shown if pan/zoom is enabled on the whole slideshow as mentioned above.