These is happening with  alot of people I have the slim and it happen to me too but you put PS3 on you title and nobody here give a crap about PS3 I seen plenty of post but no respond from the mods

I am having the same issue, MW3 either freeze's or gives me a message while getting booted out in the middle of game to get a "disc read error" message. What are these people gonna do? Mayb I should trade my sony gear and get xbox? MW3 is a good game but fix the dang issues on it, to complete game fully and functionally. getting angry cuz there are no solutions and no response.

the truth that I am very upset that pay for this game MW3 is $ 60 if I live in Honduras send it to bring a little cousin was here qeu grabs in my country.
I can not change the game for q I am in another country and I'm with that debt as saven a PS3 game worth 90 dollars in my country it costs
send him to bring to my surprise the game is bad and now I can only see and nothing else that simple and moderators of the forum or the developers have not said anything to solve the problem

Maybe the fan is working too hard to keep the system cool. Try using a vaccuum and cleaning it up. You may need a new system.

When troubleshooting console issues, there are 3 variables that could be causing the actual issue. The game disc, the game data, and the console are the 3 variables.

1. Make sure to delete all game data for the game and let it redownload any patches that it requires:

          A. Navigate to Game Data Utilities

          B. Highlight your Modern Warfare 3 game data.

          C. Press Triangle, select delete.

                    Tutorial on how to restore the file system

          1. Start with having the system in standby (redlight is on)

          2. Hold the power button down; the system will turn on and turn off once again.

          3. Press and hold the power button again and keep holding, it will beep as it turns on and then it will double beep. When you hear the double beeps immediately take your finger off the power button (if your system turns off before you get a double beep just try again and hold the button, it should double beep the 2nd time you try)

          4. You will be prompted to plug in your controller via USB and then hit the PS button

          You will now have a screen with these options :

          1. Restart System: Restarts the PLAYSTATION®3 System.

          2. Restore Default Settings: Reset all system settings back to default.

          CHOOSE THIS ONE 3.Restore File System: Checks for corrupt/missing system files.

          4. Rebuild Database: Rebuilds the OS for the PLAYSTATION®3.

          5. Restore PS3 System: Fresh restore; Deletes everything and starts from Scratch.

          6. System Update: Update the PLAYSTATION®3 System

IT IS VERY IMPORTANT THAT YOU DO NOT CHOOSE THE WRONG OPTION HERE OR YOU WILL LOSE ALL YOUR DATA.

2. Test your disc on another console. If the disc works fine on another console, the issue is not the disc. If you find that the game freezes on another Playstation 3 in the same fasion, we can begin to process a warranty disc replacement if the disc is within the 90 day warranty period and there is no damage on the disc. Please keep in mind, we test and inspect your game disc when we receive it. If we receive the disc with damage or it is no longer within warranty, we will require a 20 dollar replacement fee for the disc.

3. If the previous steps did not resolve your issue, there may be a problem with the hardware within your console and you might want to contact Sony for further support. Please keep in mind, while other games work, that does not mean that the hardware is functioning properly:

http://us.playstation.com/support/?s=ps3#ps3x

1-800-345-SONY (1-800-345-7669)

I think the latest MW3 update for the PS3 fixed the issue for the "PHAT" PlayStation.

Playstation is still turning off while playing MW3 multiplayer