When you install MT on a FreeBSD 4.9 system using:
crypt_default = blf #blowfish
on the /etc/auth.conf file, the password lenght is 60 chars so if you install MT you will never can login until you change the author_password field on the mysql.dump file.
The solution that I found to solve this problem, was to edit in my case the mysql.dump file and replace the line:
author_password varchar(40) not null,
to:
author_password varchar(60) not null.
hope this can help some one.