For me this issue has occurred for the same amount of time, the release of the x64 edition of the game. Does this issue only occur to you on the x64 edition?
As far as I know, the first issue is usually caused by the GPU Drivers, either update/rollback the driver or disable the Steam Overlay in the game.
The second issue may be caused by the same source just with a different UPE.
Obersving similar behavior:
I have recorded a video showing what happens
As for me, I have a G933, the problem happens only on 64 bit and did occur during the dev-branch