Servers Aren't Showing up in Call of Duty 4

Hi, my problem is as stated in the title. I just bought COD4 off steam and downloaded it. I manually updated the Punk Buster and enabled it in the settings. I did the install just fine. Now when I go to play online and hit refresh server list, it remains blank. Filter servers is on default settings. Windows firewall is allowing internet to pass. Firewall isn't blocking it. I've tried 2 different Wifi cards and I get nothing. I've researched the topic but can't get a clear answer to what my problem is. My brother is playing just fine on his computer so I don't know what's wrong. MW2, Battlefield and Black Ops work perfect online. Any help is appreciated, thanks.

I had this problem when I reinstalled about a month ago.. I problem for me was the servercache.dat file... I am not sure if you can see that when installing through steam (I had the disc). If you can see it, grab a copy of your brothers and rename yours servercacheOLD.dat and paste his into your folder.. Let me know if that works!

Well all of a sudden it has started working fine. It's not 100%. Have to work it a little for it to start showing up. Thanks for the suggestion.