Well, 10 year old game on a one year old Operating System... It could be the video card driver in the Windows Update prior to the most recent... maybe...
- I thought it was going to be the Steam license failing, since you could see the CD-R key, but then nothing, and since you'd changed video cards... but alas, not so. Is the game still stopping in the same place, right after you see the key flash by? After that happens, does the Silent Hunter icon on the Task Bar close? Or is it still there?