I've found the problem here ... line number 721 in wp-content/plugins/register-plus is breaking at the include of recapthcalib.php. The very last part of that page when I view source is
... name="regplus_reCAP_public_key" id="public_key" value="" /> <a href="
and it abruptly ends. Not sure why, but I just took the php code out of there and made it a dummy link and all the options show up.
Here is the broken line (721) ...
<label for="public_key"><?php _e('reCAPTCHA Public Key:','regplus');?></label> <input type="text" style="width:500px;" name="regplus_reCAP_public_key" id="public_key" value="<?php echo $regplus['reCAP_public_key'];?>" /> <a href="<?php require_once ("recaptchalib.php"); echo rp_recaptcha_get_signup_url('skullbit.com','register_plus');?>" target="_blank"><?php _e('Sign up »','regplus');?></a><br />