Please Update to version 1.7 or later of the theme and this issue will be gone.
But if you can’t update for a reason, then please check these answers:
1. Does your cache folder have the correct permissions?
You need to give your /cache/ folder full permissions. “cache” folder is located in “lib/scripts/”. In most cases this is “777” but it may vary depending on where you are hosted. If 777 does not work, try 755. It is recommended that you contact your host about what permissions to use if you are not sure. Setting permissions is also known as CHMODing, and can be done using most FTP programs and hosting control panels.
2. What path are you using for your image?
In most cases using the full path to your image should work. For example, you would input http://www.mydomain/blog/wp-content/uploads/image.jpg (or whatever the path to your image is). However, some hosts do not allow the use of http://www. at the end of a URL. In this case you should use the relative path to your image, and remove your domain from the URL. In the above case, assuming your blog is hosted in the /blog/ folder, the path to your image would just be: wp-content/uploads/image.jpg.
P.S. if this works for you, please contact me to get the modified gallery code.
3. Are you hosted with HostGator?
Please check this page, scroll to the bottom, question #11