Ninety-Four: I found a solution credited to a guy
mmarcali, it seems to be working:
1. Go to My Documents/My Games/ The Saboteur/ Save Game and find the file Config.txt and open it with any text editor (like notepad)
2. Find the line for the refresh rate and make it 60
3. Find vysinc and change it to 0
4. Write this line under the vysinc line: “Windowed 1” without the quotes
5. Save the file and run the game.
In windowed mode the game doesn't look pretty on my system but it's better than nothing.
I had a reliable freeze at a specific point of the main story were a message was supposed to open, and doing this was the only thing that solved it.
Please note that you might not need to set it to Windowed mode (i.e. skip step 4) as, at least for me, it works fine without it. (My gut feeling as a dev is that the critical race condition deadlock is solved or made much less likely by the disabling of vsynch alone)