Try resetting your translators and styles from the Advanced → Files and Folders pane of the Zotero preferences. If that doesn't help, you can try deleting the 'translators' and 'styles' folders in your Zotero data directory, but the problem may be security software on your computer preventing Zotero from writing to its own data directory.
Upgrade Storage
https://www.zotero.org/support/reporting_problems#provide_steps_to_reproduce
"Erro: Zotero was unable to load the translations and styles."
I reported the problem and this report number was generated: 1358653871