I had this problem myself. Tried the solution mentioned in this thread, which did not work. However, there was another that did (at least for me), that was written in another thread. Make the pre-boss save, change the game to windowed mode, and lower the graphics/resolution to minimum levels. Exit, run the repair, then load the save. Use Esc. or space to skip through the dialog, and hopefully you'll make it through to the dialog option as I did. After that, I raised my graphic settings back to what I had before, seems to be working.
Hope this helps.
