gethostname: unknown error

Greetings;

I have installed this software 3.55 mostly, numerous times for my students. I tried this newer version 3.56 at home on XP and it doesn't work. I have not seen this error on any of the other machines. I don't have an old version around to try out.
What does this error "gethostname: unknown error" indicate?

Thanks.

Is there any firewall between you and the server?