Perhaps the page you are retrieving is compressed. Try out this code , i haven't checked it as i don't have internet access, but i hope it works.
use strict;
use warnings;
use Compress::Zlib;
use WWW::Mechanize;
use WWW::Mechanize::FormFiller;
# Initialize a new oblect
my $mech = WWW::Mechanize->new();
# Fetch the given URL
my $url = "https://secure.secret.com/login/login.cfm?someParam=foo";
$mech->get($url);
# Throw error if page not found
$mech->success or die "Can't fetch the Requested page";
# Uncompress the page
my $dest = Compress::Zlib::memGunzip($mech->content);
# Initialize a new object to retrieve the form
my $f = WWW::Mechanize::FormFiller->new();
my $form = HTML::Form->parse($dest,$mech->base);
# Fill the form with login & password and submit
$f->fillout(user=>'xxx',password=>'xxx');
$f->fill_form($form);
my $request = $form->click();
# Fetch the next page
$mech->request($request);
# Uncompress the page
$dest = Compress::Zlib::memGunzip($mech->content);
# Retrieve the form & check for string
$form = HTML::Form->parse($dest,$mech->base);
print "$form\n";
exit 0;
I hope this works.
Neeraj.