installing firefox 0.9.3 on suse

First of all I need my dear web browser mozilla Firefox so I download the official version from mozilla project and the language pack from italian mozilla project.
After downloading I switch to root, decompress the file in /opt/firefox/ and doublecliccked on installer.
OK all seam allright... now I have to click on firefox and ... It doesn't work! SIGH!! ='[
well ... I can do it! I launch firefox from shell so I can see messages and resolve the problem:

Xlib:connection to ":0.0" refused by server
Xlib:XDM authorization key matches an existing client!
(firefox-bin:13607):Gtk-WARNING ** cannot open display

AAAAAAAAAAAAAHHHHHHHHHHHHH!!!
what should I do now?
let's do a google search and... bingo! here the solution!
I switch back to user and open a shell where I write:

su -m
password:
xhost + (switch off X authorization)
/opt/firefox/firefox-installer/firefox
et voilà! les jeux sont fait! (dont write this line on shell =D)
xhost - (switch on X authorization)

next operations: language pack and flash player!

gotta go! bye...