After G500 was installed with Windows 7 and the drivers from website, the LCD brightless can only be adjusted to the brightest or darkest level after pressing F11 & F12 key. However, it can adjust brightness normally under Windows 8.
The above symptom may occur to the following systems:
Lenovo G400\G500 shipped with panel SECLTN156AT32-L01 (18200969) with BIOS versions older than V1.07
Lenovo G400s\G500s shipped with panel SEC LTN156AT30-L01 (18200896) with BIOS versions less than V1.11.
The above symptom may occur under the following operating system:
Microsoft Windows 7