Can surf internet, but no game connection

Hello, why is it that i can connect to the internet on my playstation 3, but i can't get online for call of duty 4. I love this game, but i am so tired of the fight to connect to the server. I can surf using the internet browser, but i can't get online for call of duty!!!!!!!!! That absolutely pisses me off! Please can anyone help. Now my playstation 3 just locks up! Sometimes if i go to read a message during game play it freezes and i have to quit the game. It seems like it takes longer to boot up also, does anyone else have this problem. I sincerly appreciate all the help i can get!