Can't be bothered waiting for a response so I just went ahead and got a few answers off of the support site. If you provided system information or if you were running anything in the background such as a firewall the answer could be more exact.
Though uncommon the Master Server is sometimes unavailable. This may be due to maintenance on the server, a network outage, or simply the routing between your machine and the server over the internet. This issue will usually resolve itself if you are patient.
Be sure that your computer is not behind a software or hardware firewall of any kind. This includes firewalls built into routers or other equipment, as well as programs like Zone Alarm, Black Ice, and the integrated firewall in Windows XP and Vista. Activision does not support the use of our games from behind a firewall.
Another common cause of problems is a poorly configured router or connection sharing solution. If you are using a router, ICS, NAT or a software gateway you may have problems playing on the internet. This is because the router may not be forwarding the correct information back to your machine. It may be possible to get around this problem using port forwarding or DMZ. You can find more information on configuring shared connections for multiplayer gaming at www.practicallynetworked.com. Please be aware that like a firewall we cannot actively support using shared connections to play online.
The most common cause of problems though is usually the simplest - an overburdened network stack. By default many computers have protocols the average person doesn't use; things like VPN or NDISWAN. You may want to contact your ISP to find out exactly which protocols you can safely remove. Often times network game problems are resolved by something as simple as removing unused adapters and protocols.
* Make sure you have TCP/IP bound to only your Dial-up Adapter if you are trying to connect to the internet via dial-up modem.
* Sometimes simply rebooting your computer or power cycling the external modem can resolve this issue.
* Make sure you have the network setting set correctly in the game.
1) Start the game
2) Click on Multiplayer.
3) Ensure the right Connection Type is selected for your internet or LAN.
* If you are on a dynamic IP connection try renewing your IP address.
Windows 9x/ME
1) Click Start then Run.
2) At the prompt type WINIPCFG.
3) Once in the IP configuration screen, click Release All.
4) Click Renew All.
Windows NT/2000/XP/Vista
1) First launch the Command Prompt.
2) At the command line type "IPCONFIG /RENEW".
Be sure that your computer is not behind a software or hardware firewall of any kind. This includes firewalls built into routers or other equipment, as well as programs like Zone Alarm, Black Ice, and the integrated firewall in Windows XP/Vista. Activision does not support the use of our games from behind a firewall. If it is not possible to disable the firewall you will need to open the ports for Call of Duty 4: Modern Warfare. Call of Duty 4 transmits and receives network traffic on port 28960 using both TCP and UDP. The exact details on opening a port is specific to your firewall. For more information check with the firewall documentation or manufacturer.
Another common cause of problems is a poorly configured router or connection sharing solution. If you are using a router, ICS, NAT or a software gateway you may have problems playing on the internet. This is because the router may not be forwarding the correct information back to your machine. It may be possible to get around this problem using port forwarding or DMZ. You can find more information on configuring shared connections for multiplayer gaming at www.practicallynetworked.com. Please be aware that like a firewall we cannot actively support using shared connections to play online.
The most common cause of problems though is usually the simplest - an overburdened network stack. By default many computers have protocols the average person doesn't use; things like VPN or NDISWAN. You may want to contact your ISP to find out exactly which protocols you can safely remove. Often times network game problems are resolved by something as simple as removing unused adapters and protocols.
The problem may also be related the the status of your ISP or that of the server. Due to the dynamic nature of the internet and the variable levels of traffic, it is impossible to completely eliminate this error. If you are having persistent problems you may wish to try a different server, or just wait and play a little while later.
Make sure you're patched and install all new drivers. If that doesn't work, and you're using a router, try disconnecting it and hooking your computer straight to your modem.
Also, type in what it says where you freeze up in google and see what comes up.
Collect my card 4 secks.
