Registering Problems - unbanned users

To check out the operational of my new forum, I registered as another user - new member,
with a different e-mail address, and after a few posts, I banned the second account succesfully!

Today, to re-check the operativeness of my forum, I unbanned (succesfully) the previous account,
to the attempt on a new registering, system bannes the user by the e-mail information.
So, I re-unbanned it, but... automatically it gets banned again on the registration process!

May I have a tip to my problem, please?

Thank you very much,
yours sincerely.

PS. After that took place, system bannes every new user on the registration process by the e-mail information. The system refuses to accept any new e-mail address, and bannes the user automatically!

Please lock this thread, I've managed to solve my little problem, by my self.
Thank you very much, anyway...