Blinking screen and no X server

Question

I'm on debian since years and everything was fine. So, yesterday, I installed nvidia-cuda-toolkit and things gone bad. When I boot with kernel 4.9.0-9, I'm facing this problem : the screen is blinking and the X server doesn't start. In recovery mode, when I run startx, I get a message that no screens found. So I ran Xorg -configure, which tell me number of created screens does not match number of detected devices. But when I boot with kernel 4.9.0-8, everything is fine. I tried to delete .Xauthority but it changed nothing. Now, I'm out of ideas, so I'd like some help to resolve my problem.

Thank you.