If the Steam version is not already updated (it should be) any patches would have to come through Steam.
Did you try running the game as administrator, and in the compatibility options disable desktop composition?
Have you tried a lower / different resolution, or changing various graphics options (disable HDR lighting, etc) to see if that would help?
The person in the first aid topic with a GeForce 240 was getting an error that the renderer could not be created, which apparently can be fixed by lowering the resolution and in the options checking the "don't use desktop resolution" box.
When the conversation is over, does the screen remain black?
It isn't the same problem, but there may be some suggestions in the topic below you have not already found in the first aid topics, etc.
Never ending loading screen. 100% of the time.
