Microsoft KB Archive/105207

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PRB: KRNL386: Unable to Enter Protected Mode

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Q105207

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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

Keywords : kb16bitonly

Issue type :

Technology : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK310