DOCUMENT:Q141831 19-FEB-2002 [winnt] TITLE :System Locks Up When Accessing Floppy Drive PRODUCT :Microsoft Windows NT PROD/VER::4.0 OPER/SYS: KEYWORDS:kbenv kbhw kbHardware ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Workstation version 4.0 - Microsoft Windows NT Server version 4.0 ------------------------------------------------------------------------------- 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: KEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers 2. On the Edit menu, click Add Key. 3. Enter the following: Key Name: DisableUSWC Class: 4. Click OK and quit the Registry Editor. 5. 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 kbhw kbHardware Technology : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 Version : :4.0 ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2002.