Mozilla proxy auth

["Eduardo Gargiulo" <egargiulo@ar.homelinux.org>]

Hi all,

my linux box is hidden on a corporate intranet, where web access is
through an ISA proxy server. I'm trying to browse the web from the 
linux box using Mozilla (1.2.1), but the proxy server shows me an
error page saying that there are authentication problems.

Is there any way to force Mozilla to pop up an auth window for
filling username/password? I have an username/password with
privileges to browse the web, but I don't know how to enter
this data.

Thanks in advance

-ejg