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:
Information about my graphics card: