Can't get gksudo to work for non-root user

[Russell Blau]

Using Edgy Eft 6.10; gksudo works to run gnome applications as root, but not 
as another non-root user. The following are transcripts of terminal session 
trying various alternatives ('russell' is my username and has full sudoers 
authorization; 'dashboard' is another non-root user account on my system). 
The error messages suggest an "authentication" problem, but I'm not sure 
where to go from there.

russell at abraham:~ $ gksudo -d xterm
No ask_pass set, using default!
xauth: /tmp/libgksu-1vlFPT/.Xauthority
STARTUP_ID: (null)
cmd[0]: /usr/bin/sudo
cmd[1]: -H
cmd[2]: -S
cmd[3]: -p
cmd[4]: GNOME_SUDO_PASS
cmd[5]: -u
cmd[6]: root
cmd[7]: --
cmd[8]: xterm
buffer: -Warning: -
No password prompt found; we'll assume we don't need a password.
Warning: Tried to connect to session manager, Authentication Rejected, 
reason : None of the authentication protocols specified are supported and 
host-based authentication failed

[At this point xterm displayed, despite the error messages]

xauth: /tmp/libgksu-1vlFPT/.Xauthority
xauth_env: /home/russell/.Xauthority
dir: /tmp/libgksu-1vlFPT

russell at abraham:~ $ gksudo -d -u russell xterm
[Xterm displayed]

russell at abraham:~ $ gksudo -d -u dashboard xterm No ask_pass set, using 
default!
xauth: /tmp/libgksu-q3Z3lh/.Xauthority
STARTUP_ID: (null)
cmd[0]: /usr/bin/sudo
cmd[1]: -H
cmd[2]: -S
cmd[3]: -p
cmd[4]: GNOME_SUDO_PASS
cmd[5]: -u
cmd[6]: dashboard
cmd[7]: --
cmd[8]: xterm
buffer: -Xlib: connection-
No password prompt found; we'll assume we don't need a password.
Xlib: connection to ":0.0" refused by server
Xlib: No protocol specified
xterm Xt error: Can't open display: :0.0
xauth: /tmp/libgksu-q3Z3lh/.Xauthority
xauth_env: /home/russell/.Xauthority
dir: /tmp/libgksu-q3Z3lh
russell at abraham:~ $