cygwin xdmcp login freezes when logging into gnome, but not XFCE

Hi,

I have a Windows XP box where I've installed the latest version of Cygwin (as of two days ago). I want to use it have a remote Gnome desktop on an Ubuntu 6.10 box, where GDM has been configured to allow XDMCP logins.

Note: to allow XDMCP logins, I set the [security] and [xdmcp] sections of /etc/gdm/gdm.conf-custom like this:

[security]
DisallowTCP=false

[xdmcp]
Enable=true

On the Windows XP box, using a Cygwin bash shell, I can log into an XFCE session on the Ubuntu box just fine with the command "X -query sila :1", (then I choose XFCE session at GDM). See attached screenshot cygwin_to_remote_xfce_no_problem.png.

But If I choose Gnome session instead of XFCE, after logging in Gnome freezes as it starts up, showing only a grey rectangle in the upper left on a blue background. See attached screenshot cygwin_to_remote_gnome_has_problem.png
Gnome never makes it to the brown Ubuntu splash screen where you'd normally hear the exotic login sound.

Cygwin seems to be doing its job well, as the X server has not crashed, and works fine for XFCE. So this suggests the problem is in Ubuntu somewhere. I can't find any helpful error messages whatsoever in /var/log/ however (on the Ubuntu machine). I've "tail -f"'ed syslog, messages, user.log, daemon.log.

Also Note: if I install packages tsclient and xnest in Ubuntu, I can successfully do a XDMCP login on the Ubuntu box to itself. In other words, I can have a gnome desktop within a gnome desktop just fine this way (which uses XDMCP). So maybe it is a Cygwin issue somehow after all...

I'm not sure where the bug is: Cygwin? GDM? Some Gnome component? Maybe I need to install certain additional Cygwin packages related to X.org?