Disklavier

I have downloaded jpeg files from my Macintosh to the Mark IV to be used in the slideshow 
feature of the tablet.  I used a wireless connection to do so.

I am having a slight problem, however, for every jpeg file that I download the tablet thinks 
that I have sent 2 jpeg files instead of one and puts blanks at the beginning of the slideshow.  

Has anyone tried to download jpeg files to view in the slideshow option of the tablet?

Is there a difference in the file  structure of a Macintosh jpeg file and a PC jpeg file that might 
cause this?

Thanks,
Joan