Jan Dembowski on "Sofa Ideal Theme - Weird Error Message"

Check that theme's documentation or contact the author (it's a commercial theme).

http://themeforest.net/item/sofa-ideal-wp-business-corporate-blog/discussion/560735

That looks like a custom loop with it's own query for something specific such as a category or tag.

Since there is no matches for that query, it's displaying "Oops! No post(s) or article found."