Apple Media Player not displaying

I’ve got iTunes running on four computers (3 Macs, I Win7) but only three show in the list of available controllers when I configure Roomie Remote. All of them show up in Shared on iTunes and in my Apple TV’s.

The only things different for the missing computer is that it’s also the one running Remote Agent and it has a reserved address in DHCP.

Any ideas for things to look at?