I am brand new at this, so please keep this in mind as you read the response. ;) I don't have that plugin, though I did have a similar issue, so maybe this will help. I added a required custom field to our system for registration and it threw me into an unending cycle forcing me to update the field in the System Admin account that I was logged in as. Unfortunately, it wouldn't allow the update in the profile when I tried. I kept getting an error and then redirected back to the admin profile to update it. I had to go into the database and manually remove the field in order to break out of the cycle (I didn't try updating the database manually, which would've been safer - it's possible that would've worked too - this is a sandbox install, so I just deleted it). Perhaps if you made any of the fields required, you are having the same problem.