I have viewed your gallery in Chrome, Firefox and IE11 and the same images fail to load in all 3 browsers (for me at least), for example images 22, 23 and 24.
According to your gallery's XML file, image 22 should be located here: http://www.paulgardiner.ca/tattoos/images/4P1030659.jpg
... but going directly to that location in a browser (bypassing SimpleViewer) results in an error 404 (file not found).
It certainly looks like the file is not in the correct location on your web server.
Please double-check that the '4P1030659.jpg' file is in your '/tattoos/images/' directory.
Perhaps you could try re-uploading the image to your web server in case something happened during the initial upload resulting in a corrupt or missing file.
Also, I notice that your gallery currently uses SimpleViewer v2.1.3.
You might like to try upgrading your gallery to the current version of SimpleViewer (v2.3.2) as many bugs have been fixed since v2.1.3. (Please see the Version History for a list of changes between versions.)
I do not know if this will help but it cannot do any harm and it will rule out any bugs from previous versions which have since been fixed as being potential causes of your problem.
Instructions for upgrading existing galleries can be found on the Upgrading SimpleViewer support page.
[Query moved from SimpleViewer v1 to SimpleViewer v2 forum.]
SimpleViewer Support Team