Blank screen before video

I have put together a short captivate file as a brief portfolio of my work.  It runs very quickly and each slide is only 1.5 seconds long.  The problem is that every video I have put in starts with a blank white screen before it plays.  It is only a fraction of a second but it means that the end of the video section I selected is cut off and it makes it seem very frantic.  I don't have any transitions set in the timing and it only occurs with videos, not pictures.  Any ideas?