Lenovo T420 here with NVIDIA NVS 4200M. Upgraded to Win10... "holy crap everything works"... emmm I used last week for the first time running on batteries (no AC power)... well I found out can´t adjust the brightness anymore...
oh... the win10 driver is faulty...
Now I have a Laptop which drains the battery as fast as possible, and I need sunglasses to not get my eyes watering in the dark....
A big thanks to all the Win10 and Nvidia Intel GPU technical team for the very professional job. How can you guys have done such a beautiful mistake? Already following the rabbit in the googling hole to find out how to fix this mess.
A voice inside me is keeping bugging me:"I told you not to update..."
Thanks EEVBlog, I feel better now.