The problem is simple;
When I try to create a server, tremulous shuts down. No error message is displayed, It just cuts to the desktop. Condump revealed this:
Opening IP socket: localhost:30720
ERROR: UDP_OpenSocket: bind: Address already in use
Opening IP socket: localhost:30721
ERROR: UDP_OpenSocket: bind: Address already in use
Opening IP socket: localhost:30722
Hostname: allen-laptop
IP: 127.0.1.1
stdin is not a tty, tty console mode failed