DOCUMENT:Q172705  09-AUG-2001  [winnt]
TITLE   :Explorer Access Violates When Viewing a File's Properties
PRODUCT :Microsoft Windows NT
PROD/VER:winnt:4.0
OPER/SYS:
KEYWORDS:kbenv kbWinNT400sp4fix

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The information in this article applies to:

 - Microsoft Windows NT Workstation version 4.0 
 - Microsoft Windows NT Server version 4.0 
 - Microsoft Windows NT Server version 4.0, Terminal Server Edition 
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SYMPTOMS
========

When you use Windows NT Explorer to view the properties of a file, an access
violation occurs. If Dr. Watson is installed, it gives the standard AV pop-up
error message, for example:

   An application error has occurred and an application error log is being
   generated.

   Explorer.exe
   Exception: access violation (0xc0000005), Address 0x77f64b53

CAUSE
=====

This error can be caused if a file's property set has a corruption. In this
case, the thumbnail for the file had an empty Binary Large Object Bitmap (BLOB)
stored in the place of a CLIPDATA structure. Because Windows NT Explorer expects
the serialized CLIPDATA to have a minimum size of 12 bytes but finds the empty
BLOB to have only 8 bytes, it concludes that the discrepancy must be caused by
data corruption and exits with the above error. During the exit, Windows NT
Explorer cleaned up the allocated *CLIPDATA structure, but in so doing tried to
free CLIPDATA.pClipData, which hadn't been allocated at the point of the
failure.

The fix now zero initializes the CLIPDATA structure after allocation.

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,
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 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition
Service Pack 4.


Additional query words: prodnt

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Keywords          : kbenv kbWinNT400sp4fix 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbNTTermServ400 kbNTTermServSearch
Version           : winnt:4.0
Hardware          : ALPHA x86
Issue type        : kbbug
Solution Type     : kbfix

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