The DirectX update might have caused the problem.
I suspect that all the settings get set to the defaults, so you might want to go through the DirectX and video driver settings.

The accumulation buffer setting applies only to the OpenGL preview.
If you switch back to OpenGL, then the recommendation was to use "Software" (some people did find that "Hardware" was actually required).
YMMV as it depends a lot on individual machine setup what works best.