NMI watchdog: BUG: soft lockup - CPU#2 stuck for 23s! [plymouthd:305]
I also have the same laptop: Dell Inspiron 7559. I managed to boot by adding nouveau.modeset=0 to GRUB's linux line.
When you are in the GRUB menu, press E to enter the GRUB editor. Add nouveau.modeset=0 to the end of the line that starts with linux. After you've added it, press F10 to boot. Your system should start. After that, go to System Settings > Software & Updates > Additional Drivers and then select the NVIDIA driver. Right now I'm using NVIDIA binary driver- version 367.57 from nvidia-367 (proprietary, tested).
However I also have problems. Firstly, the NVIDIA card consumes a lot of power. My battery life is 2 hours with Linux (because it only uses NVIDIA GTX 960). With Windows I get 6 hours if I use it mildly. If I do prime-select intel, and try to log off, it gets stuck and I have to reboot it multiple times to make it boot. Sometimes it never boots back so I have to boot in recovery and switch back to NVIDIA by prime-select nvidia. I have installed all the Dell graphics card drivers and nothing changed - still doesn't boot with Intel selected. However once I managed to boot with Intel and it gave me 6:30 hours of battery life. Something is weird.
If your computer has an NVIDIA GPU add nouveau.modeset=0 kernel option to /etc/default/grub . Open the terminal and open /etc/default/grub for editing with nano text editor.
sudo nano /etc/default/grub
Append nouveau.modeset=0 inside the quotes of the line GRUB_CMDLINE_LINUX_DEFAULT="..."
Then update your grub settings with sudo update-grub .
Nano editor keyboard shortcuts
Use the keyboard combination Ctrl + O and after that press Enter to save the file to its current location.
Use the keyboard combination Ctrl + X to exit nano.
On MSI GP72 6QF Leopard Pro, I have installed Ubuntu 16.04. I installed the latest MSI BIOS firmware update as of 12/2016. Also, I have secure boot disabled and C-step disabled. Since fresh install, the Ubuntu shutdown was halting with the error:
NMI watchdog: BUG: soft lockup - CPU#5 stuck for 22s! [plymouthd:9203]
I'd get different CPU number with each shutdown.
Enabling Nvidia proprietary driver resolved the error and shutdown is successful. To enable NVIDIA driver:
In System Settings, go to Additional Drivers > Nvidia Corp > Enable Using Nvidia binary driver - version 367.57 from Nvidia...(proprietary..)
Enjoy.