Multiplayer doesn't start

[jesus]

When I click the icon or start it from singleplayer, a popup comes up saying something like "COD4 didn't close properly, do you want to run in safe mode?" Whether I click yes or no, it opens, and then crashes immediately.

What's going on?

[rolo007]

wow we basically have same system. amd 64x2 4400 + 2.3ghz
4ghz ram 8600gt wvhp 320gb sata hdd 19" acer ne way i had same problem. i reinstalled and it fixed the problem. but before you do this save you mpdata file on your desktop so you wont lose your rank. path is
c:\program files activision call of duty 4 profiles ur username

[Kradath]

I had this too and I found a fix for it. It sounds funny but it works. You have to plug in your microphone into your sound card and it'll work. Try it out.