DOCUMENT:Q105207  06-NOV-1999  [win16sdk]
TITLE   :PRB: KRNL386: Unable to Enter Protected Mode
PRODUCT :Microsoft Windows Software Development Kit
PROD/VER:WINDOWS:3.1
OPER/SYS:
KEYWORDS:kb16bitonly

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The information in this article applies to:

 - Microsoft Windows Software Development Kit (SDK) 3.1 
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SYMPTOMS
========

Windows 3.1 fails to boot and returns to MS-DOS with a "KRNL386: Unable to enter
Protected Mode" error message. This usually occurs after switching to the debug
version of Windows.

CAUSE
=====

Windows 3.1 was started with old files left over from an upgraded installation
of Windows 3.0 with the Windows 3.0 Software Development Kit (SDK).

RESOLUTION
==========

Replace the old files with the correct versions. The files of importance are
KRNL386.*, KRNL286.*, GDI.*, and USER.*. The old files are from 1990 and the new
files are from 1992. Sort by date, and replace these old files with the correct
versions.

MORE INFORMATION
================

It's generally a good idea to start with a fresh installation of Windows in a
clean directory when this problem occurs. This ensures that other obsolete files
are cleared from the upgraded 3.0 installation.

Additional query words: 3.10 no32bit

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Keywords          : kb16bitonly 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK310
Version           : WINDOWS:3.1

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