While trying to run two simultaneous NX sessions to different hosts ("home" is the alias for the second one), the connection succeeds but just before opening up the main window the dialog box pops up:

Session home failed
[Detail] [Close]

"Detail" button reveals this:

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NXPROXY - Version 3.3.0

Copyright (C) 2001, 2007 NoMachine.
See http://www.nomachine.com/ for more information.

Info: Proxy running in client mode with pid '30107'.
Session: Starting session at 'Sat Sep 12 01:09:00 2009'.
Info: Connection with remote proxy completed.
Error: Call to bind failed for font TCP port 11000. Error is 98 'Address already in use'.
Session: Session terminated at 'Sat Sep 12 01:09:00 2009'.
---

I recall being able to run at least two sessions several months ago, what could break?

client:
nxclient-3.3.0.6-alt5

first server (F10):
freenx-server-0.7.4-eter5fedora.i586
nx-3.3.0-35.fc10.i386

second server (M50):
freenx-server-0.7.4-alt16.1
nx-3.3.0-alt10