I found several discussions with this issue on windows 8 but none of the fixes seem to be working for me due to the way the drivers are behaving for me. If I change to the microsoft display driver the screen is bright but there is no brightness control and it seems to either be locked out and not adjustable or stuck in the lowest setting. With the Intel HD graphics driver I can not for the life of me get an older driver to install.
If I uninstall the current Intel driver completely, disable Windows update, and attempt to install the drivers listed on Sonys website, they never seem to actually install or show up in the device manager. The only way I can get an Intel HD graphics driver to install is by way of Windows update in which case it just reloads the same current driver that doesnt work.