This is caused by document.write usage in the local site script.

http://gd.wiktionary.org/wiki/MediaWiki:Common.js

Local administrators will have to fix their Javascript.

nadeejw wrote:

Just adding following two sites which has the same behavior.

• http://mr.wikipedia.org/wiki/
• http://en.wikinews.org/wiki/hu:Kezd%C5%91lap

Also happens on http://wikimania2007.wikimedia.org

I'm not admin there and not sure if wiki is read only now. Wikimania 2008 wiki is read only.

We have global expert users that can help local sites with issues like this btw.

They are in the global editinterface group, specifically, so that they can edit local MediaWiki interface messages, scripts and css, for sites that don't have (anymore) their own expert maintainers of this stuff:
http://meta.wikimedia.org/wiki/Special:GlobalUsers/editinterface

I see the group is a bit terse though. We might need a few more.