Hello, this is exactly why you must provide a link to your forums when requesting support. It prevents confusion for the users trying to provide assistance to you.
So,
http://entusiasti.7.forumer.com is your forum link that is having trouble registering, correct?
Here's a few things that may help:
1) Clear cookies and cache
2) Check your spam filters (as confirmation links can be sent there) if you are on free e-mail services such as Google Mail, Hotmail, Yahoo, etc . . .