CoD4 help cant play multiplayer

ok so i just got a new pc with vista monday, i looked at CoD4's requirements, all of them match. now heres my problem.
Whenever i open the multiplayer, it doesnt even start, it gives me an error message that says "It appears CoD4:MW did not quit properly last time it ran. Do you want to run the game in safe mode? This option is reccommended for most people. This will change your system settings but not your controls." then it gives me the choice of clicking yes or no. no matter what one i click, it starts to start, but just before it actually does, i get another error message whose title says, "iw3mp.exe has stopped working" and the paragraph says, "A problem caused the program to stop working correctly. Windows will close the program and notify you if a solution is available." and then it gives me one option-close program. User Acount Control is turned off. Firewall is also turned off for CoD4. The Single Player works flawlessly. I have restarted and reinstalled multiple times, but i cant get anything to work. wHAT DO I DO?!?!?!?!?!?!?!?!?!

 

try right clicking on icon and running it as admin. In Americas Army i had a similar problem (due to pb issues if not run as admin)

 

ive tried that it doesnt work, namely because my pc has only my file and therefore my file is the administrator. so thats why that doesnt work. do you have any more suggestions? can anyone tell me, on vista, how to rename that
"mssmp3.asi" file to mssmp3.bak? ive tried for like 15 minutes but it won't let me actually rename it. and by the way, i dont no anything about pc's so i need step by step instructions-FOR VISTA

 

I FIXED IT! heres how i did it (im on vista, im not sure how to do it for XP)
Control panel>Hardware And Sound>Sound>right click inside white box and click show disabled devices>click the recording tab>right click the one thats disabled (stereo mix) and enable it

and its fixed! its so much easier than the other ways posted around! no downloading anything! yay!

 

hey i have the same problem how does ur single player run i got same problem as u but i cant run multi and single player howd u get urs to work?

 

hey all i cant get on multyplayer on cod4 it comes up with some shit saying "UNABLETO INITIALIZE" and goes on about punkbuster so i downloaded punkbuster and enables it on options on cod4 multyplayer but when i click refresh servers/quick refresh nothing comes up atall its really annoying me now because i rly wanna play multyplayer!

WELL HOPE YOU CAN HELP THANKS:

 

I have the same problem with Vista. Does this change the sound settings for the game? What does that have to do with Multiplayer? Im gonna try this to see if it works for me too. just got the game yesterday. Freakn awesome!

 

Man you rock, cheers mate, I've finally got MP woking thanks to you.
Now to get all those patches...The reason servers seem empty is
because you need the latest patch installed, you must install patch 3 first:

http://www.gamershell.com/download_22318.shtml
Patch 3.


http://www.gamershell.com/download_22482.shtml
Patch 4.

http://www.gamershell.com/download_23036.shtml
Patch 5.

http://files.filefront.com/Call+of+Duty+4+Modern+Warfare+v16+Patch/;10492517;/fileinfo.html
Patch 6.

http://www.gamershell.com/download_28304.shtml
Patch 7.

This is a nice looking forum, I'll have to return some time.