It sounds like BrowserUK is right, it could be a firewall issue.
Try acessing this test script from any browser/location that doesn't work:

#!/usr/bin/perl
use strict;
use CGI;

my $q = CGI->new;
print $q->header;
print $q->start_html;
print '<ul>';

foreach my $var (keys %ENV) {
    print '<li>', $var, ' => ', $ENV{$var}, '</li><br>';
}

print '</ul>';
print $q->end_html;
[download]

This should print out some nice %ENV ironment variables for you, enabling you to eliminate your code as the source of the problem.

SMiTZ
Warning: Untested code, possible typos, possibly $author eq 'stupid + tired'