Hi Chuck,
I think I may know what is going on with this issue. I believe your images have an exif (common to digital cameras) format - true? If so, we have finally isolated a bug with exif formatted images. Those images can display correctly on the Mac but fail to display on the PC. Unfortunately, the only workaround that I have found is to save the images with a different format. We are working on this issue though.
Does that help?
Best regards,
Tricia