[groverat]

I have windows vist with all video and sound upgrades. i cant seem to play call of duty 4 online with multiplayers. the iw3mp.exe message box pops up everytime. i have no problim playing offline as a single player.

[DannyW11]

Can you give more specific information about the error message?

You double click the multiplayer .exe and what happens? What does the error message look like? Can you post a screenshot?

[Dash-X]

My friend had this problem too. I don't remember what he did, but he got it fixed.
Are u using a microphone? Try plugging it in or out if u do use it. It helped me Did u buy the game or download?
Also try running iw3mp.exe as administrator and/or in Windows XP compatibility mode.