So I continue to get emails and blog posts about issues with the High Sierra Web Drivers. I tried to log on yesterday and tell you that you were imagining things but after I installed my 121 update, I had same trouble !!!
I'm still not sure what the issue is, I have noticed that when I have the "white dock" problem it isn't that the drivers aren't loaded. I see them as loaded and I can run 2 displays at once and I can even run Uningine Valley. HOWEVER, a dead giveaway that there are issues is that moving windows results in redraws that don't include everything inside. Also, the Valley scores are about 1/2 of what they should be. Also, everything is clunky. (not very scientific, I know) But the solid white dock is the most obvious thing.
Anyhow, I tried re-installing the 117, 120, and 121 drivers. No help. I re-installed HS and tried 114, still white dock. I did PRAM reset and ran Supplemental update. No love.
Only after I did this twice have I gotten the 117 driver to work correctly again. At first it wasn't, but when I opened the Preference Pane for "Security and Privacy" there was a notice that it had blocked something from Nvidia from loading. A quick "let it load" and restart and I was off to the races. And I'm embarrassed to admit that I'm too frightened to run 120 or 121 again. I don't have 1/2 a day to track this down. I sent a note to Nvidia tech guys, hopefully the culprit is found.