I am not sure when this became an issue, but today I noticed that when I adjust the screen brightness on my laptop, it only takes effect after I either restart my computer or lower my laptop lid and raise it again. In the past, making changes to the screen brightness would take effect immediately, but lately they have not done so. I have not made any major changes to my computer recently, so the most logical suggestion I can make about the issue is that an update published by Microsoft is the source of the problem. My laptop is an HP ProBook 4540s and I am running Windows 8.1 Pro x64 with all of the latest updates installed.

I tried to resolve the issue by downloading and installing the latest graphics card driver from HP's website without uninstalling the existing installation, but that did not work. My laptop, when I am using it at home, is connected to a second monitor so that I can have a dual monitor setup. I would suggest that this was the cause of the problem, but I have used this set up for an entire year with no problems whatsoever.

No matter what I set this to, the brightness does not change immediately:

Screen Brightness

Information about my graphics card:

Graphics Card Information

  • Brightness isn't controlled by graphics driver, but special ACPI driver. Names of these drivers vary between manufacturers and usually they are completely meaningless. Try updating the rest of drivers. – gronostaj Sep 22 '14 at 13:13
  • @gronostaj Thank you for the suggestion, but it seems that the graphics card driver was the source of the problem after all. – DaveTheMinion Sep 22 '14 at 20:36

By completely removing the installation of my graphics card driver, restarting my computer, reinstalling the graphics card driver, and restarting once more, I was able to fix the problem with screen brightness adjustment. It is once again working as it should. I do not know what caused it to stop working, but since it is working again, I am satisfied.

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