Is this script OK?

I have tried everything to get this script to work but to no avail, it was taken from a fairly mainstream site (http://scripts.riffnet.com/) but it offers no direct support. A working demonstration ccan be found there. Many others at the site have reported similar problems on the forum. Can you tell me if there is a problem with the script. Currently it is modified for use with my 'freedom2surf' account and I'm pretty sure the details are correct. Beware it is quite long...

#!/usr/bin/perl

#######################################################################
# FlexBook Version 1.02 #
# Copyright 1998 by Matt Riffle All Rights Reserved. #
# Initial Full Release: 7/4/98 This Release: 2/20/99 #
# Riffnet Scripts Archive http://scripts.riffnet.com/ #
#######################################################################
# This program is free software; you can redistribute it and/or #
# modify it under the terms of the GNU General Public License #
# as published by the Free Software Foundation; either version 2 #
# of the License, or (at your option) any later version. #
# #
# This program is distributed in the hope that it will be useful, #
# but WITHOUT ANY WARRANTY; without even the implied warranty of #
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the #
# GNU General Public License for more details. It is included in #
# this distribution in the file "license.txt". #
# #
# You should have received a copy of the GNU General Public License #
# along with this program; if not, write to the Free Software #
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA #
# 02111-1307, USA. #
#######################################################################

#### Variables -- Set Accordingly

# This is the full path to your guestbook html file. Be sure
# that it is writable by the web server. In UNIX, that can
# be done with `chmod 666 gbook.html` where gbook.html is the
# name of your guestbook page.
$gbook = "gbook.html";

# This is the full path to the entry template file. For each
# variable in the form, use [varname] where you want it to
# appear in the template. To add environmental variables add a $,
# as in [$HTTP_USER_AGENT]. Another useful environmental variable
# is [$REMOTE_HOST]. [date] is a special variable that adds a date
# stamp to the entry, and [time] is a timestamp.
$template = "template.txt";

# This is the URL of the page you want displayed after a
# submission is entered. If it is set to "", a generic
# thank-you page is generated.
$success = "http://www.freeplayers.f9.co.uk/guestbook/thanks.html";

# If this variable is set to 1, new entries are added to the top of the
# list. If not, they are added at the bottom.
$add_at_top = 1;

# If you place "bad words" in this array, the guestbook will
# replace occurrences of them with ****. This, to some degree, helps
# keep foul language out of your guestbook. Comment it out if you don't
# want any filtering.
@badwords = ("gosh","heck","shucks","darn");

# This array contains the form fields that must be filled in before the
# entry can be added. Set it to ("") if no particular form field *has*
# to be entered.
@required = ("name");

# This array contains the IP addresses which are banned from using the
# site. To log IP addresses in your entries, use the special tag
# [$REMOTE_ADDR] in your template (See the README file for more info.)
# Set it to () if no one should be banned.
@banned = ();

# If this variable is set to 1, all html tags will be stripped from the
# submissions. This prevents people from including huge images or other
# such things in their entries.
$ban_html = 1;

# If your system can use "flock" for file-locking, set this variable to
# 1. Otherwise, set it to 0.
$filelock = 0;

# If this variable is set to 1, you will receive e-mailed confirmation
# each time someone adds to the guestbook.
$mail_you = 0;

# This is the path to "sendmail" on your system. On most UNIX
# systems, you can use 'which sendmail' or 'whereis sendmail'
# to find out the path. If you didn't set mail_you
# equal to 1, you don't need to set this at all.
$mailer = "/usr/sbin/sendmail";

# This is the e-mail address to send mail to, if you set $mail_you
# equal to one. Be sure to put a \ before the @, as in
# "mattr\@cgiscripts.net"
$adminaddr = "webmaster\@example.com";

###### Do Not Edit Below This Line ######

## Actions

# Check Security
&secure;

# Organize Input
&parse_form;

# Check Required Fields
&check_for_required;

# Add Entry
&add_entry;

# Mail Admin if Needed
if (($mail_you) && ($adminaddr)) {
&mail_admin;
}
# Report Success
&report_success;

## Subroutines

sub secure {

if (@banned) {
my($ban);
foreach $ban (@banned) {
if ($ENV{'REMOTE_HOST'} =~ /^$ban/) { &error("BANNED"); }
}
}
}

sub parse_form {

# Die if method is "GET"
if ($ENV{'QUERY_METHOD'} eq "GET") {
&error("GET");
}

my($ind,$value,$badword);

# Get the input
read(STDIN, $buffer, $ENV{'CONTENT_LENGTH'});

# Split the name-value pairs
@couples = split(/&/, $buffer);

foreach $one (@couples) {
($ind, $value) = split(/=/, $one);
# Un-Webify plus signs and %-encoding
$value =~ tr/+/ /;
$value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
$value =~ s/<!--(.|\n)*-->//g;
# Kill Bad Words
foreach $badword (@badwords) {
$value =~ s/$badword/****/ig;
}
# Strip HTML
if ($ban_html == 1) {
$value =~ s/<([^>]|\n)*>//g;
}

$TAG{$ind} = $value;
}

}

sub check_for_required {

if (@required) {
foreach $req (@required) {
if (!$TAG{$req}) { push (@missing,$req); }
}
}
if (@missing) { &error("MISSING"); }
}
sub add_entry {

# Create Date Stamp
my($date,$min,$hour,$day,$month,$year,$weekday,$ampm,$zero,@weekdays,@months);
(undef, $min, $hour, $day, $month, $year, $weekday) = localtime(time);
@weekdays = ("Sunday","Monday","Tuesday","Wednesday",
"Thursday","Friday","Saturday");
@months = ("January","February","March","April","May","June","July",
"August","September","October","November","December");
# Dates correct through 2097
if ($year > 97) { $year += 1900; } else { $year += 2000; }
# Fix Time
if ($hour > 12) { $hour -= 12; $ampm = "PM"; } else { $ampm = "AM"; }
if ($hour == 0) { $hour = 12; }
if ($min < 10) { $zero = "0"; } else { $zero = ""; }
$time = "$hour:$zero$min $ampm";
$date = "$weekdays[$weekday], $months[$month] $day, $year";

# Parse Template and push data to @out array
open (IN,$template) | | &error("TMPL");
while (<IN> ) {
# Handle special date tag
$_ =~ s/\[date\]/$date/ig;
# Handle special time tag
$_ =~ s/\[time\]/$time/ig;
# Handle Environment Variables
$_ =~ s/\[\$([^\]]*)\]/$ENV{$1}/ig;
# Handle form input tags
$_ =~ s/\[([^\]]*)\]/$TAG{$1}/ig;
push (@out,$_);
}
close(IN);

# Open guestbook and get entries
open (GUEST,$gbook) | | &error("GBR");
# This should be more efficient, really
@lines = <GUEST>;
close (GUEST);
# Write New Guestbook File
open (NEW,">$gbook") | | &error("GBW"