[Guy Harris <guy@xxxxxxxxxx>]

> Now on the command line when I give ethereal, it gives me a warning
> 
> Gtk-WARNING **: cannot open display:
> 
> I am running as root.
> Has anyone seen this before?

Yes, on Debian, although I think the message might've been more helpful
than the one you got (i.e., it might've said *why* it couldn't open the
display).

X servers can do some level of authentication for connections; see the
"xhost" man page.  At least on Debian as it's set up on my Debian
partition at home, the X server rejects attempts by a program running as
root to connect to it unless I've explicitly allowed those requests with
"xhost".  Try running some other X applications as root; if they all get
"can't open display" or similar problems, it's probably an access
control problem.