Database Failure on Emails Module

Hi, I´m having trouble using the Email Client of the SuiteCRM.

When any user, except admin, click on E-mails, gives “Database Failure, please see sugarcrm.log for details”.

When admin goes to Emails, it works perfectly. But when normal uses try, gives the above error.

I looked on suitecrm.log, but nothing is there. Just a message “index.php doesn´t exists in the specified directory”. But I don´t think this message is about that, because when I refresh the page, the message doesn´t appears at the same time.

Anyone have this problem ?