User themes and administration not working after sign-up.

Hello,

The process of new users registration is working fine.
However, when accessing the front and back-end as an user is all messed-up.
The site and the administration does not display correctly. it looks like there are no CSS.

http://www.karthaz.com/roberto/

What I'm I doing wrong? Please help!

Thanks in advance,

Linhares Junior