This article was previously published under Q330303
The problem that the "Symptoms" section describes can occur in other versions of Windows. To find the Microsoft Knowledge Base article that applies to you, see the "Similar problems and solutions" section.
When you try to log on to a domain on a Windows 2000-based computer, a Winlogon error dialog box briefly appears. Then, you receive the following Stop error message:
STOP: c000021a (Fatal System Error) The Windows Logon Process System process terminated unexpectedly with a status of 0xc0000005 (0x0000000 0x00000000). The system has been shut down.
This problem occurs if the fully qualified domain name (FQDN) of your computer is exactly 200 bytes long. During logon, one character more than the 200-byte allocation is written and heap corruption occurs.
Service pack information
To resolve this problem, obtain the latest service pack for Microsoft Windows 2000. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
260910 How to obtain the latest Windows 2000 service pack
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.
Date Time Version Size File name --------------------------------------------------------- 24-Oct-2002 01:33 5.0.2195.6102 46,864 Secur32.dll
To work around this problem, rename the computer so that it is one character shorter. If you do this, the FQDN is less than 200 characters long and the heap corruption does not occur.Because you cannot log on to the domain, log on as the local administrator of the computer to change the computer name.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Microsoft Windows 2000 Service Pack 4.
For more information about how to obtain a hotfix for Windows 2000 Datacenter Server, click the following article number to view the article in the Microsoft Knowledge Base:
265173 The Datacenter program and Windows 2000 Datacenter Server product
Similar problems and solutions
If you still experience the problem that is described in this article, you may have a similar but different problem.For more information about similar problems in Windows 2000 or Windows XP and resolutions, click the following article numbers to view the articles in the Microsoft Knowledge Base:
156669 How to troubleshoot a "STOP 0xC000021A" error
823736 Your computer restarts unexpectedly when you press CTRL+ALT+DELETE to unlock your computer
811412 Installing Internet Information Services can cause problems in Windows XP
318666 Internet Explorer maintenance policies may cause an access violation in Winlogon
311804 Your computer hangs when you log on to a Terminal Services session
308299 "Stop 0x21a" error message occurs if you download a RIPrep image
If these Microsoft Knowledge Base articles do not help you resolve the problem, or if you experience symptoms that differ from those that this article describes, please search the Microsoft Knowledge Base for more information. To search the Microsoft Knowledge Base, visit the following Microsoft Web site: