DOCUMENT:Q234658  20-MAY-2002  [winnt]
TITLE   :STOP Error in CSRSS After Attempting to Free a Screen Buffer
PRODUCT :Microsoft Windows NT
PROD/VER:winnt:4.0,4.0 SP1,4.0 SP2,4.0 SP3,4.0 SP4,4.0 SP5
OPER/SYS:
KEYWORDS:kbWinNT4sp6fix

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The information in this article applies to:

 - Microsoft Windows NT Server version 4.0, Terminal Server Edition 
 - Microsoft Windows NT Workstation versions 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3, 4.0 SP4, 4.0 SP5 
 - Microsoft Windows NT Server versions 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3, 4.0 SP4, 4.0 SP5 
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SYMPTOMS
========

When you run a program as a service that constantly creates and closes consoles,
the following blue-screen error message may be displayed when you log off the
computer:

   STOP: c000021a {Fatal System Error}
   The Windows SubSystem system process terminated unexpectedly
   with a status of 0xc0000005 (0x77f7d40f 0x187fd70).
   The system has been shut down.

The parameters for the status 0xC0000005 can vary.

CAUSE
=====

This problem occurs because a screen buffer owned by CSRSS is freed by a
process. During the freeing process, the screen buffer's reference count is
incremented. When the screen buffer's reference count decrements to 0, an
attempt is made to free the screen buffer. Because the screen buffer has already
been released (freed), this causes an access violation, which leads to the Stop
0xC00021A.


RESOLUTION
==========

Windows NT Server or Workstation 4.0
------------------------------------

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the
individual software update. For information on obtaining the latest service
pack, please go to:

 - http://www.microsoft.com/Windows/ServicePacks/

-or-

 - Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack

For information on obtaining the individual software update, contact Microsoft
Product Support Services. For a complete list of Microsoft Product Support
Services phone numbers and information on support costs, please go to the
following address on the World Wide Web:

   http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS


Windows NT Server 4.0, Terminal Server Edition
----------------------------------------------

To resolve this problem, obtain the latest service pack for Windows NT Server
4.0, Terminal Server Edition. For additional information, please see the
following article in the Microsoft Knowledge Base:

   Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack


STATUS
======

Microsoft has confirmed this to be a problem in Windows NT 4.0 and Windows NT
Server 4.0, Terminal Server Edition.

This problem was first corrected in Windows NT Server 4.0 Service Pack 6 and
Windows NT Server 4.0, Terminal Server Edition Service Pack 6.

WORKAROUND
==========

To work around this problem, lock the workstation or server instead of logging
off. However, this may not be a practical workaround in certain instances.

Additional query words:

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Keywords          : kbWinNT4sp6fix 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTW400sp5 kbWinNTW400sp4 kbWinNTW400sp3 kbWinNTW400sp2 kbWinNTW400sp1 kbWinNTSsearch kbWinNTS400sp5 kbWinNTS400sp4 kbWinNTS400sp3 kbWinNTS400sp2 kbWinNTS400sp1 kbWinNTS400search kbWinNTS400 kbNTTermServ400 kbNTTermServSearch
Version           : winnt:4.0,4.0 SP1,4.0 SP2,4.0 SP3,4.0 SP4,4.0 SP5
Hardware          : ALPHA x86
Issue type        : kbbug
Solution Type     : kbfix

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