*hmm* Daniel, it's possible that the go account is locked out with YOUR IP address, so when you go back it's seeing that and keeping you out.
From what I understand, you get the board index because you have to log in for the system to pay attention to who you are, before it'll lock you out.
ETA: I played around with the mod a little bit. If you don't want to ban peolpe by IP address when you ban them from their profile, go to EnhancedBan.php, find
$aToBan[count($aToBan)] = "ID_MEMBER = '" . $aMember['ID_MEMBER'] . "'";
$aToBan[count($aToBan)] = "Name = '" . $aMember['memberName'] . "'";
$aToBan[count($aToBan)] = "Mail = '" . $aMember['emailADDress'] . "'";
$aToBan[count($aToBan)] = "IP = '" . $aMember['memberIP'] . "'";
and change it to
$aToBan[count($aToBan)] = "ID_MEMBER = '" . $aMember['ID_MEMBER'] . "'";
$aToBan[count($aToBan)] = "Name = '" . $aMember['memberName'] . "'";
$aToBan[count($aToBan)] = "Mail = '" . $aMember['emailAddress'] . "'";
Also, if you notice in the first of these blocks, there's a type:
emailADDress, which has the caps for the D's and won't actually import the email address for the user!
Change the DD to dd and you should be fine. I tested this on my 1.5.2 board today and it's okay.