it's a warning, so nothing really to worry about. And if you type it in google: http://www.google.nl/search?q=%22Using+non-qualified+column+reference%22&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:nl:official&client=firefox-a
Wow... a bug report and a fix. Please search a little befor posting. Some of us read all posts and have to try to assess whether it is a real problem. This cost me 5 minutes for this post.