If the game crashes and gives you a black screen immediately following the loading screen, try this:
Find the file "user.cfg" in the main System Shock 2 directory.
Open the file using Wordpad, or any program that can read text files.
The document should be blank.
Type the following line:
safe_texture_manager
Now, save the file, and the game should run fine.
Hope this helps!
-Alezunde