Gtk error only when root! (??)

["Camilux" <camilo@cancun.com>]

Hi,

im having this *very* strange error in deb 2.2 , ximian gnome...

if i am not root, i can for example open gdmconfig, but it says i 
need to be root to change things; so i su - myself up to root, but 
when i type gdmconfig, i get this error:

Gtk Error: Can't Open display

same when triying to install the mozilla binary... if not root, the 
graphical installation screen pops up, but of course i cant install 
sh*t... so i su to root, and same Gtk error... 

whats wrong here?

thanks...
camilo