Example in the crmex-log file
2011-11-22 09:23:16,127 INFO [CTP-byj #7] Establishing connection to Exchange [email@example.com]..
2011-11-22 09:23:22,690 ERROR [CTP-byj #7] INVALID_LOGIN: Invalid username, password, security token; or user locked out.
This error normally indicates that the user changed the Salesforce account password and now Riva is using the wrong password in the connection. The Riva connection object is not aware of any password changes made by the user or a Salesforce system administrator.
Follow the How to reset Salesforce password procedure to reset the password in the Riva Salesforce connection for the specified user.