try adding the ibt parameter;
open this file:
kate /etc/default/grub
and in this line: GRUB_CMDLINE_LINUX_DEFAULT inside the quotes add this parameter:
ibt=off
dont remove anything from there!, just add it to existing parameters, save the file, update grub:
sudo update-grub
install the nvidia drivers:
sudo mhwd -a pci nonfree 0300
and if there are errors post them here, if not, reboot