Microsoft KB Archive/141831

= System Locks Up When Accessing Floppy Drive =

Article ID: 141831

Article Last Modified on 10/31/2006

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APPLIES TO


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

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This article was previously published under Q141831





SYMPTOMS
When you attempt a drag-and-drop operation on files, either to or from a floppy disk, the system may stop responding.



CAUSE
Some high performance video cards enable Uncached Speculative Write Combining (USWC) memory. In combination with some motherboard BIOSes, this may cause a memory conflict in the Graphical User Interface (GUI), which may cause the system to stop responding.



RESOLUTION
To resolve this problem, you can either boot using the VGA mode or add the following registry key:

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.


 * 1) Start Registry Editor (Regedt32.exe) and locate the following Registry subkey in the HKEY_LOCAL_MACHINE subtree:


 * 1) On the Edit menu, click Add Key.
 * 2) Enter the following:

Key Name: DisableUSWC

Class:
 * 1) Click OK and quit the Registry Editor.
 * 2) Shut down and restart Windows NT.

The presence of the DisableUSWC key will cause the miniport to not use USWC. With USWC disabled, the memory conflict will not occur and the system will not stop responding for this reason.



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

Additional query words: hang freeze frozen hung lock locked stop stopped halt halts halted gui ui prodnt

Keywords: kbenv kbhardware KB141831

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