There's an issue with one of your page files on 6.9 where simply having the plugin installed corrupts and makes the entire webUI unusable
The "blank" area is because of
<br />
<b>Warning</b>: syntax error, unexpected '=' in Unknown on line 13
in <b>/usr/local/emhttp/plugins/dynamix/include/PageBuilder.php</b> on line <b>34</b><br />
<br />
<b>Warning</b>: syntax error, unexpected '=' in Unknown on line 13
in <b>/usr/local/emhttp/plugins/dynamix/include/PageBuilder.php</b> on line <b>34</b><br />
<br />
<b>Warning</b>: syntax error, unexpected '$' in Unknown on line 17
in <b>/usr/local/emhttp/plugins/dynamix/include/PageBuilder.php</b> on line <b>34</b><br />
Which only happens when the VM plugin is installed. Unfortunately those line numbers don't really refer to anything in particular due to how PageBuilder.php actually works, but process of elimination points right at one of the .page files