I have WikEd installed and whenever I create a new page (user talk page and in template creation) and click on wikEd small preview button twice then i click on normal usual preview button. It shows Main_page with the content replaced.
It may be related to WikEd. I also raised the bug in en:w:User:Cacyle/wikEd_development page.
You can see the history.
Thanks
Version: unspecified
Severity: normal
URL: http://ta.wikinews.org