New install, opening index displays script contents or error

I’ve just installed RT 3.0.10-3 from rpm (using yum) on a RedHat 9.0
(Shrike) system and am having a few issues.

I upgraded perl (from source) to 5.8.4 as RT would not run on the standard
5.8.0 installed as part of the system. I have Apache (httpd-2.0.40-21) and
mod_perl (mod_perl-1.99_07-5) from the standard rpm packages. I’ve
customised my /etc/rt/, made the necessary changes to
/etc/httpd/conf.d/rt.conf and added “Include /etc/httpd/conf.d/rt.conf” to
/etc/httpd/conf/httpd.conf. rt-setup-database ran smoothly with the options
I chose.

Issue is that when I point my browser at http://localhost:80/ I get:

%# BEGIN LICENSE BLOCK %# %# Copyright (c) 1996-2003 Jesse Vincent %# %#
(Except where explictly superceded by other copyright notices) %# %# This
work is made available to you under the terms of Version 2 of %# the GNU
General Public License. A copy of that license should have %# been provided
with this software, but in any event can be snarfed %# from %#
%# This work is distributed in the hope that it will be useful, but %#
WITHOUT ANY WARRANTY; without even the implied warranty of %#
Public License for more details. %# %# Unless otherwise specified, all
modifications, corrections or %# extensions to this work which alter its
source code become the %# property of Best Practical Solutions, LLC when
submitted for %# inclusion in the work. %# %# %# END LICENSE BLOCK
<SNIP rest of script, I think you get the picture…>

I think at this stage I should be getting script output not the script
itself. If I go connect from another machine I get:

Internal Server Error
The server encountered an internal error or misconfiguration and was unable
to complete your request.

Please contact the server administrator, root@localhost and inform them of
the time the error occurred, and anything you might have done that may have
caused the error.

More information about this error may be available in the server error log.

Additionally, a 500 Internal Server Error error was encountered while trying
to use an ErrorDocument to handle the request.

Apache/2.0.40 Server at Port 80

Can anybody help me with this?

Thanks in advance.