You cannot log on to an Exchange Server computer when you are running Outlook (268575)


The information in this article applies to:

  • Microsoft Outlook 2002, when used with:
    • Microsoft Windows XP Professional
  • Microsoft Outlook 2000, when used with:
    • Microsoft Windows XP Professional
  • Microsoft Outlook 98, when used with:
    • Microsoft Windows XP Professional
  • Microsoft Outlook 97, when used with:
    • Microsoft Windows XP Professional
This article was previously published under Q268575
NOTE: The procedures in this article only apply if you have installed Outlook with the Corporate or Workgroup option. With this option, you can use Messaging Application Programming Interface (MAPI) services. To determine your installation type, click About Microsoft Outlook on the Help menu. If you have the Corporate or Workgroup installation, you see "Corporate or Workgroup".

SYMPTOMS

When you attempt to connect to a Microsoft Exchange Server-based computer and you are running Outlook on a Windows 2000 Professional-based or Windows XP Professional-based computer, you may receive any of the following error messages:
The Microsoft Exchange address book was unable to log on to the Microsoft Exchange server computer. Contact your system administrator if the problem persists.
Your logon information is incorrect.
Outlook could not logon.

CAUSE

Cause 1

This behavior occurs because the Transmission Control Protocol/Internet Protocol (TCP/IP) stack is initialized incorrectly.

Cause 2

This behavior can also be caused if the following registry key is corrupted or missing:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\ClientProtocols

RESOLUTION

Resolution 1

To resolve this behavior, uninstall and then reinstall TCP/IP from the Windows 2000-based computer. For more information about how to uninstall and install TCP/IP, see the "More Information" section of this article.

NOTE: Remove TCP/IP as your last step after you have tried all basic troubleshooting steps.

Resolution 2

To replace this registry key, export the key from another computer, and then import it on the affected computer.

MORE INFORMATION

For more information about how to troubleshoot before you remove TCP/IP, click the following article numbers to view the articles in the Microsoft Knowledge Base:

195795 How to troubleshoot Outlook 2000 configuration problems

258495 Troubleshooting client connectivity issues by using command-line utilities

167260 How to use RPCPing to Test RPC communication

174701 Troubleshooting RPC problems for Exchange clients

How to Uninstall TCP/IP

  1. Log on as the local administrator.
  2. Close all open programs, and then disable any anti virus program.
  3. Right-click My Network Places on your desktop, and then click Properties.
  4. Right-click Local Area Connection, and then click Properties.
  5. Click Internet Protocol (TCP/IP), and then click Uninstall.
  6. You receive the prompt to uninstall TCP/IP, click Yes.
Your computer restarts.

How to Reinstall TCP/IP

  1. Log on as the local administrator
  2. Right-click My Network Places on your desktop, and then click Properties.
  3. Right-click Local Area Connection, and then click Properties.
  4. Click Install, and then click Protocols.
  5. Click Add.
  6. Click Internet Protocol (TCP/IP), and then click OK.
  7. Click Close in the Local Area Connection Properties dialog box, and then restart your computer.
  8. Log on to the network, and then verify that Outlook resolves the Exchange Server name and the mailbox name.
Modification Type:MinorLast Reviewed:11/17/2005
Keywords:kberrmsg kbnetwork kbprb KB268575
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