I have installed Call of Duty Modern Warfare, but I can't open Multiplayer. It keeps saying iw3mp.exe has stopped working. I have installed the correct DirectX version (came with my windows 7 pro), but it keeps saying the same message. Any idea how it is possible why it won't open? Single player opens just fine.
It looks like the problem here is your OS. Some of these older games were only ever tested on the current Operating System(Windows XP for this game). As new ones get released, it gets hard to guarantee these games will work 100% since they were never tested on these OS's. You can try and run the game in compatibility mode, but that is a hit or miss sometimes.
One way around this however, is through steam. With a little touch of magic, they are able to run older games like this through the steam client. If you wish to enjoy Call of Duty 4, then this might have to be the route you take.