Microsoft KB Archive/183840

= Stop 0xC000021A When Starting Task Manager with CTRL+ALT+DEL =

Article ID: 183840

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Server 4.0, Terminal Server Edition
 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows NT Workstation 4.0 Developer Edition

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This article was previously published under Q183840





SYMPTOMS
The Task Manager can be started by pressing CTRL+ALT+DEL and then clicking Task Manager on the Security dialog box. However, if there are many user environment variables defined, running Task Manager from the Security dialog box may cause a STOP C000021A exception error message.



CAUSE
The System Environment Block becomes corrupted by the Winlogon service if the size of the User Environment is significantly large. This can also be caused by the installation of many applications on a system.



RESOLUTION
To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

152734 How to Obtain the Latest Windows NT 4.0 Service Pack



STATUS
Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.

Additional query words: environment winlogon crash hang

Keywords: kbhotfixserver kbqfe kbbug kbfix kbqfe KB183840

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