keyboard problems keys not always work

Hello,

My asus S46cm, under windows8 has some trouble with the keyboard (Azerty). Several keys sometimes dont work for hours (most often Q,D,G,K,I). Sometimes all keys work. I have update all drivers and i have no trouble with external keyboard.

Could you help me please

After a complete reinstall, everything was ok for two weks. But when i activate my screen saver, the problem comes back.

Help, Help!