Italian Module for OS X Dictionary.app

http://www.spider-mac.com/2010/09/04/l-plug-in-dizionario-italiano-per-leopard-e-snow-leopard/

OS X 10.7 Lion: Fixing Mixed Localization Problems

I've seen several reports in the Apple Discussions from users who have system alerts or other menus/dialogues in two languages at once, such as English and Arabic, or English and Danish.

A possible fix for this is to go to system preferences/language & text/language and use the Edit button to uncheck the box for the language you don't want and then restart.