This sometimes happens with some users, and the culprit most often is
the graphics card/Display driver being automatically updated.
So im almost certain that is what has happened to you, so double check on
that, and if it is so, you can easily roll back the driver.
Steve Rhoden (Cow Leader)
Film Maker & VFX Artist.
Owner of Filmex Creative Media.
Samples of my Work and Company can be seen here:
https://www.facebook.com/FilmexCreativeMedia