Article ID: 268575 - View products that this article applies to.
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".
When you attempt to connect to a Microsoft Exchange Server-based computer and you are running Microsoft Outlook on a Microsoft Windows 2000 Professional-based or a Microsoft 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 1This behavior occurs because the Transmission Control Protocol/Internet Protocol (TCP/IP) stack is initialized incorrectly.
Cause 2This behavior can also be caused if the following registry key is corrupted or missing:
Resolution 1To 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 2To replace this registry key, export the key from another computer, and then import it on the affected computer.
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:
(http://support.microsoft.com/kb/195795/ )How to troubleshoot Outlook 2000 configuration problems
(http://support.microsoft.com/kb/258495/ )Troubleshooting client connectivity issues by using command-line utilities
(http://support.microsoft.com/kb/167260/ )How to use RPCPing to Test RPC communication
(http://support.microsoft.com/kb/174701/ )Troubleshooting RPC problems for Exchange clients
How to Uninstall TCP/IP
How to Reinstall TCP/IP
(http://support.microsoft.com/kb/255843/ )Unable to log on to Exchange Server from a Windows 2000 or Windows XP client
Article ID: 268575 - Last Review: January 27, 2007 - Revision: 3.1
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