If computer does not shutdown completely, one fix is to add pci=nomsi option to the grub settiongs.

sudo nano /etc/default/grub

…. edit the next lines as

GRUB_CMDLINE_LINUX_DEFAULT="pci=nomsi"
GRUB_CMDLINE_LINUX="pci=nomsi"

…. save, quit and update grub

Ctrl o
Ctrl x

sudo update-grub