LCD Brightness control doesn't work after resume from sleep/hibernatio

Hi,
Occasionally, when resume from hibernation/suspend, display brightness control doesn't work. Means that Fn + F2,F3 doesn't work, change from Windows Power Options doesn't work, change from intel graphic doesn't work.
Anyone know if I have to restart some services to get it working? It's occasional and I can't find anything exact in EventLog.
My system is HP Probook 4230s with Core i5-2410 with intel HD3000. Latest patches on both Win 7 Pro 32-bit and intel driver.
Restart machines solve the problem, re-hibernate or re-suspend machine occasionally solve the problem, but mostly not.

See if HP have an update for their firmware or function key control drivers. I know its a new pc, but its worth a shot.

I already have latest ones including the BIOS.