I had the same problem and first i try to install an other version of the game (english version instead of the french CD), it worked some weeks then i got the same crashs again.... Then I search on google the solution....
http://www.tomshardware.co.uk/forum/99190-25-cod4-crashes-opening-join-servers
I give you an extract :
1. Make a new profile in the game.
2. go to Program Files/Activision/Cod 4/Players/Profiles/(the new account)
3. Copy the new CFG file (config_mp.cfg) to the profile that can't browse the server list
4. Open the config_mp.cfg file and press Ctrl + H (replace) [if it says you need to select a program. click take program from a list and use notepad]
5. Put the name of the new profile in the first box, and your old profile in the second. Press Replace all. Save the file.
6. Take the file config.cfg (NOT config_mp.cfg) out of the file to your desktop. (you can always put it back) if you dont have config.cfg it doesn't matter.
6. Repeat step 4 for config.cfg
7. Go in game, and it should work.
Note: You might lose Singleplayer saved games