Chiming in that I, too, am having Directx11 issues. This only started after patch 6.01 installed. Never had an issue before. I am currently just playing in Directx9. I have updated drivers and windows, and as I read forums it seems there is no actual fix. Just random whether it a fix helps permanently, temporarily, or not at all.

Note the game will load, with no sound, if I don't click the "OK" box in the error dialog box.