Microsoft KB Archive/927840

= Keyboard input may be displayed very slowly after you upgrade a computer to Windows Vista =

Article ID: 927840

Article Last Modified on 3/15/2007

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APPLIES TO


 * Windows Vista Business
 * Windows Vista Enterprise
 * Windows Vista Home Premium
 * Windows Vista Home Basic
 * Windows Vista Ultimate
 * Windows Vista Business 64-bit edition
 * Windows Vista Enterprise 64-bit edition
 * Windows Vista Home Premium 64-bit edition
 * Windows Vista Home Basic 64-bit edition
 * Windows Vista Ultimate 64-bit edition
 * Windows Vista Starter

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Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows registry



SYMPTOMS
After you upgrade a computer to Windows Vista, keyboard input may be displayed very slowly. For example, you may type many characters before any characters are displayed on the computer screen. Additionally, CPU usage may spike when you use the keyboard. This behavior may momentarily freeze the system.

This problem occurs when you use a PS/2 keyboard or a wireless keyboard that uses a PS/2 adapter.

Note This problem does not occur if you use a USB keyboard.



CAUSE
This problem occurs if a keyboard setting is not migrated correctly during the upgrade. A registry subkey controls the delay time that occurs after each key input. If this registry setting is lost during the upgrade, the delay time is set to the default value of 12 milliseconds (ms). Therefore, the system waits 12 ms after each key is pressed.



RESOLUTION
Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To resolve this problem, follow these steps:  Open Registry Editor. To do this, click Start, type regedit in the Start Search box, and then click regedit.exe in the Programs list.

If you are prompted for an administrator password or for confirmation, type the password, or click Allow. Locate and then click the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\i8042prt\Parameters

 Double-click PollStatusIterations, and then type 1 for the value. Exit Registry Editor. Restart the computer.

Keywords: kbtshoot kbexpertisebeginner kbprb KB927840

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