You receive error message and are continuously prompted for your Windows NT domain credentials in Outlook 2000, Outlook 2002, or Outlook 2007

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Article ID: 321652 - View products that this article applies to.
This article was previously published under Q321652
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SYMPTOMS

When you start Microsoft Outlook, you may receive one of the following error messages:
Your logon information was incorrect. Check your username and domain, then type your password again. If your account is new or if your administrator requested a password change you need to click Change Password then logon with your new password.
-or-
The logon credentials supplied were incorrect. Make sure your username and domain are correct, then type your password again.
When you start Outlook against your Microsoft Exchange Server mailbox, you receive a prompt for your Windows domain credentials multiple times. After you receive several prompts, you finally gain access to the server. However, you may receive more prompts during the session.

CAUSE

This behavior occurs because the system registry may be missing one or more values in the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\ClientProtocols
The following values are the core required values for Windows XP or Windows 2000:

Collapse this tableExpand this table
NameTypeData
(Default)REG_SZ(value not set)
ncacn_http REG_SZRpcrt4.dll
ncacn_ip_tcpREG_SZRpcrt4.dll
ncacn_npREG_SZRpcrt4.dll
ncacn_nb_tcpREG_SZRpcrt4.dll
ncadg_ip_udpREG_SZRpcrt4.dll

The following values are the core required values for Windows 98:

Collapse this tableExpand this table
NameTypeData
(Default)REG_SZ(value not set)
ncacn_np REG_SZRpcltc1.dll
ncalrpcREG_SZ
ncadg_ip_udpREG_SZRpcltc3.dll
ncacn_httpREG_SZRpcltccm.dll

Following the system's protocol binding order, you receive a prompt for credentials on each missing value until a value that matches the next protocol in the binding order is reached.

RESOLUTION

Use one of the following methods to resolve this behavior.

Method 1

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


Import a valid registry key from a computer that is working correctly. To do this:
  1. Start Registry Editor (Regedt32.exe).
  2. Locate and then click the following key in the registry:
    KEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\ClientProtocols
  3. Click the ClientProtocols key.
  4. On the File menu, click Export.
  5. Save the file with a .reg or a .txt extension in the event you need to send the file by using Outlook. You must save and rename the attachment to a .reg extension to import the key.
  6. Quit Registry Editor.
  7. Rename the file that you just exported from a .txt file extension to a .reg extension, and then copy it to a folder on your computer.
  8. Start Registry Editor (Regedt32.exe).
  9. Locate and then click the following key in the registry:
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\ClientProtocols
  10. Select the ClientProtocols folder, click File, and then click Import.
  11. Select the .reg file that you saved, and then click Open.
  12. Quit Registry Editor.
  13. Quit and then restart Outlook 2002.

Method 2

Use Registry Editor to manually create the missing values. To do this:
  1. Start Registry Editor (Regedt32.exe).
  2. Locate and then click the following key in the registry:
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\ClientProtocols
  3. Click Edit, click New, and then click String Value.
  4. Edit the new string value with the name and data information that is in the table in the "Cause" section of this article.
  5. Repeat steps 3 and 4 for each missing value.
  6. Quit Registry Editor.

Properties

Article ID: 321652 - Last Review: June 1, 2007 - Revision: 6.1
APPLIES TO
  • Microsoft Office Outlook 2007
  • Microsoft Outlook 2002 Standard Edition
  • Microsoft Outlook 2000 Standard Edition
  • Microsoft Exchange 2000 Server Standard Edition
  • Microsoft Exchange Server 5.5 Standard Edition
Keywords: 
kbregistry kbpermissions kberrmsg kbprb KB321652

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