No Mouse or Keyboard After Installing Logitech MouseWare Version 8.x (255151)

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

CAUSE

This behavior can occur if the Microsoft Windows NT 4.0 drivers for Logitech MouseWare have been installed. Installing MouseWare loads the following services and drivers:

Added services:

Lkbdfktr.sys, which is the Logitech Keyboard Class Filter driver.
Lmoufltr.sys, which is the Mouse Class Filter driver.
Lsermous.sys, which is the Logitech Serial Mouse driver.

All three of these drivers are set to a Start value of System.

The L8042prt.sys driver is copied to the %SystemRoot%\System32\Drivers folder.

The registry entry for the mouse and keyboard is changed to:

HKEY_Local_Machine\System\CurrentControlSet\Services\i8042prt:Imagepath=System32\Drivers\L8042prt.sys

RESOLUTION

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

The fastest way to get mouse and keyboard functionality back is to use Recovery Console to replace the file, and then use Registry Editor to change the reference to the correct file:

Start the computer to Recovery Console.
Change to the %SystemRoot%\System32\Drivers folder.
Type the following lines, pressing ENTER after each line:
ren l8042prt.sys l8042prt.lgt copy i8042prt.sys l8042prt.sys disable lkbdfltr disable lmoufltr disable lsermous
Type exit to quit Recovery Console, and then reboot the computer.
After the computer reboots, start Registry Editor.
Change the registry entry for the mouse and keyboard to:
HKEY_Local_Machine\System\CurrentControlSet\Services\ i8042prt:Imagepath=System32\Drivers\i8042prt.sys
Note that the entry is using a lowercase "L" in the name. L8042.sys should be changed to i8042prt.sys.

MORE INFORMATION

The third-party products that are discussed in this article are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.

REFERENCES

302971 Stop 0x1E or Stop 0xc5 After You Install Service Pack 2 and You Use Logitech Mouse Drivers