Help for halo demo (pc)?

ok, i downloaded the halo 1 free trial version from microsoft for the PC. It does say that you are allowed to play one map on muliplayer (PC) but whenever i want to join a game online it dosn't even list a list of games and when i press refresh it says "unable to connect to the gamespy master server." Does anyone know how to fix it?

-most likely its your firewall blocking it... check and make sure that halo is an allowed program.