Not sure if this is more of a Mac problem or Ubuntu. I am trying to set up my Ubuntu machine to accept multiple remote sessions from different computers (Mac, Windows, etc.) Since VNC only seems to allow one session (and is limited to the physical screen connected to the computer) I started looking for other solutions and found XDMCP. Now I am not to familiar with what this actually does, but it seems to halfway work. Here is my issue:

I think I have everything setup on Ubuntu. On my Mac (G5 with OSX 10.5.5) I run Xnest to start an X windows session in a window and set -query to my Ubuntu machine. The login window comes up and I can log in fine, then Gnome starts up and the menu bars come up and it seems I have about 5 seconds where I can click on menus and such until everything locks up and I get a wristwatch icon and can no longer do anything in the Xnest window (Mac is still fine though).

Anyone know why this would be locking up on me and what I could try to resolve this issue???