05-13-2018 06:49 AM
Hi, I have the same problem.
I have a question, after you fixed the brightness issue, do you have problem with projecting to other screen? (using VGA port or HDMI port) ?
because in my case, if I fixed the brightness problem (by roll-back driver) then I can not project to other screen.
please let me know
12-16-2018 09:49 AM
Here goes a little update
After upgrading Windows 10 to each new version (170x and 180x) the problem comes back.
Recently, Microsoft changed the location of the FeatureTestControl key. Now it is located in:
The key FeatureTestControl must be to hex value "f048"
In my z400, I've found 3 keys (0000, 0001 and 0002). When I changed the first, the others were changed too. It's always good check it.
After reboot, the brigthness buttons were working fine