That flashing you are talking about is actually caused by the graphic drivers and compatibility with the Windows 10 operating system. I recommend closing down the game and then apply a compatibility tweak. Right click the executable of the game and then go to Properties > Compatibility. Select a previous version of Windows from the list and then accept all the changes and launch the game. If you still encounter issues, press ALT + Enter to switch back the game into Window mode. This mode usually works without glitches or visual errors.