Displaying SetsBrowser Info Environment
It will create resized versions of each image on your server (for performance reasons), so if your server isn't allowing that, it could be the cause of the issue.
A couple things you can check:
1) File permissions on the packages/jb_gallerific folder (should be 755 for folders and 644 for files).
2) A PHP component may be missing from your server (GD) - but this is unlikely as you would have noticed other problems as well.
Hope this helps.