Comment 12 for bug 1773113

I had a variant of this problem (on Lenovo P51, M2200 Nvidia):

After upgrade from 17.10, where everything worked fine, to 18.04 the laptop still booted normally (I DID get login and desktop) but when I suspended or locked the screen I also got black screen and curser in upper left corner.

Now everything more or less works again by using this workaround from Bug #1752053 posting #123:

---------snip----------------
I found a silly workaround (after trying many many other suggestions / driver re-installs), now using nvidia-driver-396 or nvidia-driver-390; create (if not exists) a file /etc/rc.local, with this content:

#!/bin/bash

sleep 1

exit 0

And make it executable: chmod 755 /etc/rc.local
---------snip----------------

Maybe this helps some people.