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Microsoft KB Archive/171643

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Knowledge Base

Winlogon Hangs at the Log On Screen

Article ID: 171643

Article Last Modified on 10/31/2006


  • Microsoft Windows NT Server 3.51
  • Microsoft Windows NT Server 4.0 Standard Edition
  • Microsoft Windows NT Workstation 3.51
  • Microsoft Windows NT Workstation 4.0 Developer Edition

This article was previously published under Q171643


Windows NT 4.0 Winlogon stops responding (hangs) at the logon screen after creating a blank system-environment variable.


Windows NT 3.5x causes the computer to stop responding (hang) and displays the following error message:

c000021a fatal system error
The winlogon process has terminated unexpectely with a status of
0XC00000005 (0X000000000 0X000000000)


You need to restart the system before you are able to log on to the computer again.


Microsoft has confirmed this to be a problem in Windows NT version 4.0. We are researching this problem and will post new information here in The Microsoft Knowledge Base as it becomes available.

Keywords: kbbug kbenv kbpending KB171643