LXDE dual monitor: no display on boot

Question

I run LXDE with Ubuntu 16.04 on a computer with 2 screens. I installed ARandR to be able to display the desktop on both screen, and I saved the configuration so that it is run on login. It works fine, but I get an issue when shutting down and restarting the computer:

• If both screens are plugged when booting, grub appears on second screen (I have dual boot), then nothing: screens are completely black. Second screen displays message of lost signal. I have to press start button to shut the computer down.
• If I unplug the HDMI wire of the second screen before booting, everything is fine: I get to the login screen, and I can plug back the screen. After login, desktop is displayed on both screens.

Thanks for helping

Answer 1

The issue was caused by screens driver. I had to use NVIDIA proprietary driver in Preferences -> Software and Updates -> Additional Drivers and select NVIDIA driver.

Then, in console I run the command nvidia-xconfig to create the xorg file, and nvidia-settings to set the screens.