Microsoft KB Archive/92901

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Mouse Problems with Swap File and LRU Settings


The information in this article applies to:

  • Microsoft Windows versions 3.1, 3.11


This article discusses using least recently used (LRU) paging settings in the [386enh] section of the SYSTEM.INI as a possible solution to erratic mouse behavior when a swap file is active.

You should use these steps only after you have determined that a mouse problem is present only when Windows 3.1 is configured to use virtual memory.


If you experience missed mouse clicks or jerky mouse movements in Windows while a swap file is active, you may need to adjust the frequency of the LRU rate in Windows.

Missed mouse clicks are mouse button actions that seem to be ignored by Windows. A "stuck" mouse button or click refers to a situation in which Windows seems to lock the mouse button down. This locking causes a "runaway" effect when scrolling. Scrolling will seem automatic for up to a few seconds.

The LRU settings are outlined on pages 205-206 of the Windows Resource Kit for Windows 3.1 and, in general, these settings should not be changed. To determine if your mouse problem is related to the swap file LRU settings, place the following line in the [386enh] section of your SYSTEM.INI:


If this setting does not improve Windows mouse movement, then general mouse troubleshooting should be performed. The LRU settings should not be changed.

Microsoft has an article available that outlines general mouse troubleshooting. The article "Troubleshooting Microsoft and Compatible Mice in Windows" (Q88543) can be obtained by contacting Microsoft Product Support Services.

If testing with "paging=off" resolves the erratic mouse symptoms, remove the "paging=off" statement from the SYSTEM.INI file and add the following lines to the [386enh] section of the SYSTEM.INI:


This sets the low LRU rate = to the high LRU rate.


This sets the high LRU rate, the default is 250 (1/4 of a second):

   x=60000 = 1 Minute
   x=600000 = 10 Minutes
   x=6000000 = 1,000 Minutes (about 16 hours)
   x=60000000 = 10,000 Minutes (about 6 days)
   x=600000000 = 100,000 Minutes (about 60 days) 

Try 60000 first; if that behaves, try 600000000.

NOTE: You may need to experiment some to determine the proper LRU settings.

These settings adjust how Windows uses virtual memory. Different settings for LRUSweepFreq may be needed depending on if a temporary or permanent swap file is used.

For more information about erratic mouse behavior, see the "Mouse Pointer Movement Is Erratic" section in the following article in the Microsoft Knowledge Base.

Q88543 Troubleshooting Microsoft and Compatible Mice in Windows

Additional query words: 3.10 jumpy

Keywords : win31
Issue type :
Technology : kbWin3xSearch kbWin310 kbWin311

Last Reviewed: September 24, 1999
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