Hm. Odd... it shows on initial page view, but as you said it goes away on refreshing the page; yet the source shows the exact same URL for the image.
I wonder if it has something to do with your .htaccess file, perhaps the rewrite is rewriting the image URL?
It's a bit difficult to pick through the source since it's such an ugly table-based layout.
You also might want to check the validation; 90 errors is a bit much.
http://validator.w3.org/check?uri=http%3A%2F%2Fwww.seguridadalimentariaonline.com%2F&charset=%28detect+automatically%29&doctype=Inline&group=0