I have a Gateway PC AMD 64 x2 with Vista home. When I bought COD4 I kept getting the iw3mp.exe error and by way of the forums found out that it was my Realtek Hi Def sound drivers. Once I uninstalled these drivers everything worked fine but then last week I get this ATI 3850 with built in HD audio and now not only does the multi player not work but the single player has stopped as well. I have tried reinstalling the game and I deleted/disabled everything known to man but as soon as I double click the COD 4 icons these errors pop up. Oh by the way my nvidia 7600 GS 512mb worked fine before I installed the 3850.[/b]
Hi and welcome to the forums. Did you completely remove the old Nvidia drivers before installing the 3850? Have you tried loading the latest drivers for your 3850 from the AMD website? What is the spec on the rest of your system? COD4 the only game you are having problems with?
One of the guys in my gaming clan was getting the realtek error. It was fixed simply by plugging a set of headphones into the jack and removing them when the game starts.
I just found a solution for those of you who have problems playing multiplayer because of iw3mp.exe problem. this will sound dumb but it works. plug some headphones or a microphone into the MICROPHONE port on your computer then try again. yes it works i dont know why, i just did it myself. please sticky for the many people that have this problem.
Eisen6faust 
