I, I got cod4 for months and I played often but for a reason when I was in game I made Alt+tab and an error screen pop-up and I had to close the game. But when I open it after, I go to join server, and there is no server.. I click on refresh and nothing appears. An the source is internet, and I tried a couple of stuff but I'm not realy good at computer problems... sry for my bad english.
I would use an external server browser such as HLSW or Xfire if I were you as the in-game one has always been screwed up.
use ur cable box turn it off for 3 to 4 mins with the computer off and that might help