I read somehwere here that because of the latest Intel video drivers for the 6730B, the FN F7/F8 keys to control the brightness don't work anymore. It's the case on my laptop. Including the FN-F4 to switch to outside displays. So I can't do a presentation. All FN keys related to the video have absolutely no effect whatsoever.
Those keys work at boot time while, for example, in the BIOS window. No problems.
I have started Windows XP Pro SP3 in safe mode, also disabled all drivers, services, unchecked everythin in msconfig, etc... no way. Impossible to adjust the brightness.
I'm about to reinstall the very first version of the video drivers (fortunatelly it's still on the driver web site pages) but I'm fearing though that the BIOS should be downgraded too.
There have been many posts on the forums about the function keys not working on HP notebook keyboards in connection with Windows XP SP2 and especially SP3. Also broken was the On Screen Display for volume adjustment. This all hinges upon the driver for the keyboard being installed correctly. Many downloading the HP drivers found they installed only the QLB functions but not the Fn key/OSD functions. When trying to manually install the driver, the Device Manager would complain simply the installation "failed" and the keyboard driver would remain the "Standard 101/102-Key or Microsoft Natural PS/2 Keyboard" and not show the appended "with HP QLB" as is needed.
It took me about 4 days of troubleshooting to track down and solve the problem definitively, so I decided to save everyone else the trouble and post what I did here.
The problem is with the Microsoft Windows Driver Foundation in the operating system not being installed correctly. The HP QLB keyboard driver relies on version 1.5 of this driver. If you are having problems with the WDF, you should see an error log in the WINDOWS directory of the filename Wdf01005Inst.log and an error section like this one:
0.015: ================================================================== ============== 0.015: 2009/07/13 17:14:46.250 (local) 0.015: c:\a2584604a3eea9210734ad\update\update.exe (version 126.96.36.199) 0.015: Hotfix started with following command line: /quiet 0.015: In Function GetBuildType, line 1170, RegQueryValueEx failed with error 0x2 0.015: C:\WINDOWS\system32\DRIVERS\wdf01000.sys is Present 0.015: FileVersion of C:\WINDOWS\system32\DRIVERS\wdf01000.sys is Greater Than 1.5.5600.0 0.015: Condition Check for Line 1 of PreRequisite returned FALSE 0.015: ReadStringFromInf: UpdSpGetLineText failed: 0xe0000102 0.015: Wdf01005 Setup encountered an error: Setup cannot continue because one or more prerequisites required to install Wdf01005 failed. For More details check the Log File c:\windows\Wdf01005Inst.log 0.015: ReadStringFromInf: UpdSpGetLineText failed: 0xe0000102 0.015: Setup cannot continue because one or more prerequisites required to install Wdf01005 failed. For More details check the Log File c:\windows\Wdf01005Inst.log 0.015: Update.exe extended error code = 0xf0f4 0.015: Update.exe return code was masked to 0x643 for MSI custom action compliance. 0.031: ================================================================== ==============
The solution is to delete the files wdf01000.sys and wdfldr.sys in windows/system32/drivers. In my case I also searched for all occurrences of the wdf01000.sys file in the registry (including a service) and deleted those.
Then reinstall the HP QLB driver appropriate for your model, and you should be good to go. This worked for me on my 6530b model laptop.