I can't diagnose this without being able to view Special:Preferences, which I can't do without an account, which I can't create other than through a Citizendium-like request procedure. Can you give me a test account so I can poke at this?

Thanks for setting me up with a test account.

This line appears in the HTML source of your pages and should be removed:
<script type="text/javascript">var $j=jQuery.noConflict();</script>

Although of course the real issue is that some modules aren't properly wrapped in (function($) { ... })(jQuery); , which should really be done for *all* modules by the resource loader itself. Repurposing this bug for that.

(In reply to comment #2)

Although of course the real issue is that some modules aren't properly wrapped
in (function($) { ... })(jQuery); , which should really be done for *all*
modules by the resource loader itself. Repurposing this bug for that.

This was done in r79246. I also fixed some JS errors on the preferences page in r79245.

I confirm that the root cause for the failing preferences is the jQuery.noConflict() setting.