@Dan, I too receive an error:
Warning: array_key_exists(): The first argument should be either a string or an integer in ********\wp-content\plugins\document-gallery\models\class-document.php on line 140
This error is present only when NOT logged in and, interestingly, appears before my main post content. The document gallery still appears where I've inserted the dg shortcode:
[dg orderby="menu_order"] within the content of my post.
I'm running WP 3.8 on a localhost install, Version 1.4.1 of Document Gallery plugin.
Also, if this has any relevance, the icon displayed for the document type .htm is DIFFERENT when logged in vs. logged out. I thought that is odd. The other filetypes I have displayed don't change icons when logged in or out.
Logged in icon displayed for .htm file: /wp-content/plugins/document-gallery/icons/html.png
Logged out icon displayed for .htm file: /wp-includes/images/crystal/code.png
Finally, this error is printed five times, which is the number of documents in the gallery with the .htm filetype. I am not seeing this error on other pages or posts using the
[dg] shortcode where there is not a .htm file in the gallery (though I haven't tested out on other doc types).