Nautilus cannot start from MacOSX 10.4/X11

Binary package hint: nautilus

Login to Ubuntu 6.10 from MacOSX 10.4 via "ssh -X" and start nautilus on the command line it terminates with the following messages.

$ nautilus

(nautilus:4162): Gdk-WARNING **: Connection to display localhost:15.0 appears to be untrusted. Pointer and keyboard grabs and inter-client communication may not work as expected.

(nautilus:4162): libgnomevfs-WARNING **: Failed to open session DBUS connection: Unable to determine the address of the message bus (try 'man dbus-launch' and 'man dbus-daemon' for help)
Volume monitoring will not work.

(nautilus:4162): Gdk-WARNING **: Coercing GDK_INPUT_ONLY toplevel window to GDK_INPUT_OUTPUT to work around bug in Xorg server
The program 'nautilus' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadAtom (invalid Atom parameter)'.
  (Details: serial 163 error_code 5 request_code 18 minor_code 0)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

Running from another Ubuntu machine works fine and sees the same DBUS warning message.