I don't have any kind of a "save" button in the plugin interface on the Add New, Add Directory and Categories pages; therefore I cannot add files to the system at all.
I viewed the source of the Add New page and these are the last lines in it, so I assume it breaks:
<th scope="row"><strong>Categories</strong></th> <td><div id="categorydiv"><ul class="categorychecklist" style="background: #fff; border: 1px solid #DFDFDF; height: 200px; margin: 4px 1px; overflow: auto; padding: 3px 6px; width: 346px;">
The above occurs in all browsers I have installed (Chrome, Firefox, Opera, Internet Explorer and Safari for Windows).
Funny enough, on a different server, with classic cpanel environment and multisite, it works properly.