Ok... sound card.... do you get this error? iw3mp.exe has stopped working?
If your game shows no error just get a black screen, back to desktop, 1 - make sure all firewall is shut down, heres how to do that:
Right click on My Computer> click Manage> double click services and applications> double click services> Scroll down to Windows firewall> make sure it doesnt say started> also check windows defender> NOTE: you may want to turn these back on when not playing the game... your personal preferance.
2. If your getting the black screen or instant shut down without any error do as follows>
Right click on your cod4 desktop link> Click properties> Click compatibility tab at top > check the run as administrator button.> click apply.
Now when you start game it will ask for permition, but atleast you get to play.
If you do get an error message, please post what your error message is.