I had the same error showing up in log file every time i tried to change into full screen-mode. As soon as i selected a full screen instead of borderless window the game just hang up with black screen, requiring a reboot and editing of config file back to borderless window-mode before i could play again.
Yesterday i installed Msi Afterburner and lowered the power limit from 100% to 97 or so, and after that the full screen mode worked flawlessly and i get no more errors.
My graphics card is Msi Gtx 970 Gaming, and it has never been overclocked since there is no need for that as the card is fast enough as it is..so essentially i had to downgrade the cards original power values.
But the needed amount of tuning down is so minimal it won't practically affect framerates at all.
Anyway, main point is that now i can finally play in full screen mode, and hopefully this same solution works for some others here who are having the same problem.
Edit: Seems i still get random crashes in fullscreen mode, witcher3-crashinfo files in game directory give the same error as before: "Crash reason: EXCEPTION_ACCESS_VIOLATION (3221225477), Error writing location 0xbc1f3c97" (this location changes every time).
However this time the screen does not turn black as before, game just freezes and shuts down after a while.
Maybe i should downclock my graphics card even more, or just stick playing in borderless window-mode until the game is patched. Nothing wrong with my system; every other game works normally, i7-4790k processor with 16 gb ram should also be enough for this game.
So this seems to be some kind of error with games directx-functions, hopefully they find and fix the fault soon..