Hi Eric
the user_Registration page line 91 is: $WA_redirectURL = ""; as you said it should be so doesn't look like a problem there.
In the users_Login.php page I inserted the code: <?php var_dump($_SESSION); ?> on line 260 just above: <h1>Enter your login information</h1> as you asked and get the result:
array(0) { }
not quite sure what this is telling me so you may have to guide me through please.