I've also noted the how-to in the body of this article just for posterity, but please, support all the Mac sites by reading the original over on MacFixIt!
The problem is in a file called inetd.conf. Here's how you fix it, as described by Mike Vannorsdel in the forum thread:
Open a terminal session, and edit /etc/inetd.conf. Change the last line from
#ident stream tcp wait root /usr/libexec/tcpd identd -w -t120to
auth stream tcp wait root /usr/libexec/tcpd identd -w -t120Save the changes and reboot, and you should be good to go!

