Mmmh, have you tried rebooting your mac? I know it's not common, but a full reboot might solve it. Maybe there is another instance of 0 A.D. you need to kill. @Langbart have you ever seen this?
EDIT: Logs would help.
Interesting.
I don't know for sure, but I'd say it didn't exist when this forum was created, nor when we were using the previous software. It has to be noted though, that IRC has been quite a standard in the FOSS world.