You need to contact the manufacturer of your notebook about Windows 7 support since they make the drivers that communicate with operating system.
Andre Da Costa http://adacosta.spaces.live.com http://www.activewin.com
Best, Andre Windows Insider MVP MVP-Windows and Devices for IT twitter/adacosta groovypost.com
Okay, a few moments after I posted my last message, Windows Update offered me a driver update for my NVIDIA GeForce 9300M GS - and guess what, screen brightness works just fine now.
So for all of you who have an NVIDIA GeForce 9300M GS - go to Windows Update, for all others, be patient - a driver update will most likely fix your problem soon!