Registration Problem...

There is something wrong with the registration for my forum : www.inexus.pureforum.net
When someone tries to register, and is up to the part where it asks you to confirm Password, when he confirms, he goes back to the register page. I tried registering it for him but the same thing happened. Also, since there is this problem with registering which means no one has registered on my forums yet, when he chooses the name Batman, it says the username has being taken already...? Help, please. This problem hasn't occured to the other forums I made : www.maplealley.quickbb.net I've checked the settings for both of them which matches.

Thank you.

Have you checkedin the inactive user list?