You cannot adjust your portable computer's LCD display contrast or backlight controls in Windows XP

Support for Windows XP has ended

Microsoft ended support for Windows XP on April 8, 2014. This change has affected your software updates and security options. Learn what this means for you and how to stay protected.

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When you use Microsoft Windows XP on a portable computer, you may not be able to adjust the contrast or the backlight controls on your LCD display. Additionally, CreateFile() function calls to open the \\.\LCD device may return an "ERROR_FILE_NOT_FOUND" error message.This problem may occur when the following conditions are true, in the order that they are presented in:
  • You start your portable computer without a connected CRT monitor.
  • You connect a CRT monitor to your portable computer.
  • You switch the display from the portable computer LCD display to the CRT monitor, and then you switch it back to the LCD display.
This problem is caused by a conflict in the video port component of Windows XP that occurs during the enumeration of the Advanced Configuration and Power Interface (ACPI) devices that are connected to the computer. ACPI devices are display devices such as LCD displays or CRT monitors.

Service pack information

To resolve this problem, obtain the latest service pack for Microsoft Windows XP. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
322389 How to obtain the latest Windows XP service pack

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

File information

The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
Windows XP, 32-bit editions
   Date         Time   Version        Size    File name   ---------------------------------------------------------   18-Jun-2004  18:14  5.1.2600.1545  71,168  Videoprt.sys
Windows XP, 64-bit editions
   Date         Time   Version        Size     File name   ----------------------------------------------------------   18-Jun-2004  18:14  5.1.2600.1545  284,800  Videoprt.sys
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Microsoft Windows XP Service Pack 2.
For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates

Article ID: 843617 - Last Review: 12/08/2015 07:35:34 - Revision: 2.7

Microsoft Windows XP Professional, Microsoft Windows XP Home Edition

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