okay well. im running windows vista 32 bit and the game can run perfectly fine but there is no sound. there IS sound in windows though and all my other files (music, games etc) all work perfectly fine and sound fine. when i play cod4 though there is no sound. the in-game sound options are all turned on, set to windows default, volume to the max, speakers are not muted. i was even playing once and i can hear people sign in and out of AIM. i downloaded it through steam maybe that is the problem

Are all your drivers up to date?

If that doesn't work then try this:

1. Go to Control Panel
2. System
3. Device Manager
4. System Devices
5. Right click System Devices then click Scan For Hardware Changes
6. Occasionally this process must be done twice
7. Check CoD4 for sound