Outlook 2007 prompts you repeatedly for a password under certain network conditions

Under certain network conditions, Microsoft Office Outlook 2007 prompts you repeatedly for a password. If you do not enter a password or if you enter an incorrect password, Outlook 2007 may silently enter Offline mode. In this case, you do not receive an error message or a notification, and you will not be connected to the mailbox.

How to enable the hotfix

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756  How to back up and restore the registry in Windows

To enable the hotfix, follow these steps:

1. Exit Outlook 2007.
2. Start Registry Editor.
   • In Windows Vista, click Start
     
     , type regedit in the Start Search box, and then press ENTER. 
     
     
     
      If you are prompted for an administrator password or for confirmation, type the password or provide confirmation.
   • In Windows XP, click Start, click Run, type regedit in the Open box, and then click OK.
3. Locate and then click to select the following registry key:
   HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\RPC
   Note If the RPC key does not exist, follow these steps:
   1. Right-click the Outlook key, point to New, and then click Key.
   2. Type RPC, and then press ENTER.
4. After you select the key that is specified in step 3, point to New on the Edit menu, and then clickDWORD Value.
5. Type UseWindowsUserCredentials, and then press ENTER.
6. Right-click UseWindowsUserCredentials, and then click Modify.
7. In the Value data box, type the value that you want to use, and then click OK.
   
   Note When you set the UseWindowsUserCredentials value to 1, only the user's desktop credentials will be used. The following scenarios may help you determine the value that you want to use.
   • Account: Domain 
     UseWindowsUserCredentials: 0 (or not present) 
     Protocol: TCP, HTTP with NTML authorization
     Result: Connect to Microsoft Exchange without prompting for user credentials.
   • Account: Non Domain
     UseWindowsUserCredentials: 0 (or not present)
     Protocol: TCP, HTTP with NTLM authorization
     Result: Prompt for user credentials and connect to Microsoft Exchange.
   • Account: Domain
     UseWindowsUserCredentials: 1
     Protocol: TCP, HTTP with NTLM authorization
     Result: Connect to Microsoft Exchange without prompting for user credentials.
   • Account: Non Domain
     UseWindowsUserCredentials: 1
     Protocol: TCP, HTTP with NTLM authorization
     Result: Does not prompt for user credentials, and will not connect to Microsoft Exchange. Remains in the disconnected state, occasionally trying to connect.
   • Account: Domain
     UseWindowsUserCredentials: 1
     Protocol: HTTP with Basic authorization
     Result: Prompts for user credentials and successfully connects to Microsoft Exchange. Additionally, it will continue to prompt you if you mistype your password.
   • Account: Non Domain
     UseWindowsUserCredentials: 1
     Protocol: HTTP with Basic authorization
     Result: Prompts for user credentials and successfully connects to Microsoft Exchange. Additionally, if you mistype your password, it will continue to prompt you.
   • Account: Domain
     UseWindowsUserCredentials: 1
     Additional Steps: When you configure the profile, select Always prompt for username and password.
     Result: Prompts for user credentials and successfully connects to Microsoft Exchange.
8. On the File menu, click Exit to exit Registry Editor.

You can use the following registry entry to disable the credentials prompts when you receive an authentication error on credentials. 

HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\RPC\DisableTransientFailureAuthPrompts (DWORD) 

(default to FALSE, 1 is TRUE, and 0 is FALSE) 

You can use the following registry entry to set a timeout period. If we do receive an authentication error, attempts to acquire another set of credentials will fail for a timeout period set in this registry entry. 

HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\RPC\TransientFailureBackoff (DWORD)

(defaults to 10 sec, 10000 sec - 10 sec)


http://support.microsoft.com/kb/956531