Ubuntu 18.04 crashes when second monitor connected by hdmi

Question

When I connect a second monitor to my laptop (HP Pavilion dv6 2130er, NVIDIA GX 320m) with Ubuntu 18.04 by HDMI, it's freezing and doesn't respond to any actions until rebooted. When I reboot the laptop with the monitor connected it works fine but, when I turn HDMI off and on again, it freezes.

sudo lshw -class display

  *-display                 
       description: VGA compatible controller
       product: GT216M [GeForce GT 320M]
       vendor: NVIDIA Corporation
       physical id: 0
       bus info: pci@0000:01:00.0
       version: a2
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress vga_controller bus_master cap_list rom
       configuration: driver=nouveau latency=0
       resources: irq:26 memory:d2000000-d2ffffff memory:c0000000-cfffffff memory:d0000000-d1ffffff ioport:6000(size=128) memory:c0000-dffff

Answer 1

The solution may be as simple as installing the updated pro Nvidia drivers:

First add the drivers PPA:

sudo add-apt-repository ppa:graphics-drivers/ppa
sudo apt update && sudo apt upgrade

Then from "Activities" window, search for "Software & Updates" and run said program. Under the "Additional Drivers" tab you will see a list of available drivers. Select the one with the highest version number. When it finishes installing reboot. If X starts up without a hitch, you should be good to go.

If X doesn't start, and instead drops you to a command line, purge out the nvidia drivers:

sudo apt purge "*-nvidia-*"
sudo apt autoremove && sudo apt autoclean

Then reboot, and follow the above instructions again, but this time selecting the next driver in the list. In my case driver 396 does NOT work for me but 390 does. Once you find the driver version that works after reboot, your dual monitors should work.