I have an Asus laptop with Windows 8 and fn+f5/fn+f6 keys (for brightness) doesn't work. In fact, they work, but they can increase/decrease the brightness only 1 time. I mean - after pressing fn+f5 once, nothing happens if I try to press fn+f5 again, before I press fn+f6. This only happens after logging in. At the login screen and during Windows boot I can adjust the brightness as I want, but after login I can't. I installed the latest ATK driver and NVIDIA graphics driver for Windows 8, and I think that my problem is related to conflict with drivers. I tried to reinstall/delete some drivers, but it didn't help. How can I detect where is the problem? Thanks.