Have just resolved this one - followed instructions on another posted link - http://wordpress.org/support/topic/files-at-not-loading-in-tree
inspected details of intranet site in chrome - found was hanging on the Ajax tree view.
Any folders in the view showed the child elements with a spinning
"url(images/ajax-loader.gif) 0 0 no-repeat;"
leaving the link as:
<span class="placeholder"> </span>
When I right clicked on the folder and opened up in a new tab, the contents were then viewable - unless it was another folder in which case you got a placeholder for the new folder...
Fabian had posted -
"Francis Penny, jQuery is not loaded on your blog. Disable any CDN/jQuery Plugins, its not WP-Filebase.
CorpoCluj, it seems you have at least one plugin installed that produces invalid line breaks on every page. Take a look at your pages source. Disable other plugins, again thats not WP-Filebase fault."
so took advice and went back through plugins - sure enough as soon as I disabled one running auto xml updates - the Ajax view sprang back to life!
Glad I did not have to go through a re-installation of wordpress - yakaroo, if your site was previously working and has recently stopped, it really is worth going back through your plug ins, it worked for me - hope it works for you!