Ok, so my brothers and I have been playing Civilization 4 against each other for a while now with no problems. We are in the same house and going through the same router and everything is fine.

However, we recently started trying to play with friends who of course are in different locations. When we do this the game works fine for about ten minutes before we all lose our connections and have to quit and re-load the game.

Is this a problem with our internet, the game, or what?

Yes , its an internett problem ,i think the routers have a firewall on.

use hamachi (www.hamachi.cc) it solves similar problems. or it could be a firewall. check out whether your windows firewall (in case of xp) have civ on the exception list