Like in Call of Duty 4, users may have problems with the Modern Warfare 2 multiplayer or single player executables crashing or failing to launch.
iw4sp.exe has stopped working
As always, the default advice is to make sure you have all of your drivers updated including graphics drivers and your audio/sound card drivers.
iw4mp.exe has stopped working
AMD.com | Support & Downloads
Drivers - Download NVIDIA Drivers
Creative Worldwide Support > Sound Blaster
Dell - Drivers and Downloads
HP United States - Computers, Laptops, Servers, Printers and more
ASUSTeK Computer Inc.-Support-
You may also try plugging in a microphone, that worked with the iw3mp.exe error in Call of Duty 4.
If you have had success solving these issues, please share with the rest of us in this thread.