I have had the same problem. Currently I am trying to sort out my hostname which is causing squid to fail (for me). Perhaps that might be the case for you too.
I too am using RH9 so what I did - which has worked for me - was to edit squid.conf and change the following for
TAG: visible hostname
Do this with squid shutdown or do a reconfigure (squid -k reconfigure)
This presumes that you have a domain name. I don't know what you should do if you haven't or whether it will upset anything else. Perhaps someone else can answer that. Maybe you could use www.yourname.yourisp.com
From my (limited) understanding of this, it is used by squid for messaging. If there is a page that cannot be reached for example, squid will issue a warning to the user. It will say it is from squid at your domain.
Best of luck. Can't guarantee it will work and so if it doesn't - undo the change and ask again.
If anyone can shed light on why squid can't pick up the hostname - I would be interested too as I think it is the root of my problems with fetchmail/sendmail