[Ygorl]

I wouldn't mind running it PBEM, but this happens whether I am playing on a network-hosted version of the game or just playing as though it were a local, non-network game (i.e. "Play an existing game"). It's not the case that I can't serve games (I've had no problems serving them in the past, and have always played them by logging in to 127.0.0.1), it's just a problem with this game.
Ironhawk, sounds like the broken pipe is simply a side-effect of the client crashing. Thanks. Arralen, I checked the ownership and privileges; the files belonged to group "staff" instead of group "admin" (which owns the rest of my games) but changing that didn't fix anything.

After just now typing all this, though, I remembered that I don't have the map installed on this machine. Sheesh. Now I feel dumb... Thanks everyone for the help!