Create Thumbnail Gallery in Media Library Problem

Hi folks,
I am having a problem with the default Media Library Gallery when I try to insert it into a post or page. If I choose display as slideshow, it works fine, but if I try to use thumbnails, all the main image area does is show the loading cycle icon and never displays a picture. I can’t figure out what is wrong or why it won’t work.

Anyone have any ideas? http://landscaperpa.com has lots of gallery slideshows but the thumbs don’t work at all.