Looks like the fix is this: # If you need to disable # gfxpayload=keep on your system, just add this line (uncommented) to # /etc/default/grub: # # GRUB_GFXPAYLOAD_LINUX=text
So, try just adding the above, then run "update-grub" to activate the change. The problem seems to be some GPU cards have faulty UEFI graphics, and switching grub to "text" mode works around the problem. There is even a set of already blacklisted GPUs in this file: /boot/grub/gfxblacklist.txt
