OnPreRender: The request failed with HTTP status 401: Unauthorized

SYMPTOM

    I recently installed or have been using the web part and it is 
    displaying an error: The request failed with HTTP status 401: Unauthorized 
    
    CAUSE


    An unauthorized error may be a legitimate error which signifies 
    that the user account which is configured for a component or logged into the 
    server or site does not have sufficient permissions to access another 
    necessary component such as a product's web service, a configured 
    item, Active Directory, etc.

    RESOLUTION

   Please recheck the account to verify that the account being used has proper permissions.