Try a simple script:

#!/usr/local/bin/perl -w
use strict;
use CGI;
my $cgi = new CGI;
print $cgi->header(-type    =>  'text/html');
print "Please use <CODE>your code here</CODE> tags";
[download]

chmod 755 the script. If it does the same, check your webserrvers configuration.

update ps. your script works fine for me, it's probabluy your webservers configuration.