@Wizard I think the problem isn't there because I already tried installing version 3.0.4 and I got the same problem. =\
Anyway, I already installed phpBB in my server but I had to copy the DB from my local server and manually change the config.php file.
I want to change my Main Domain from roitudo.heliohost.org to yyyyy.heliohost.org, if possible.
I didn't send a PM because "All support PMs sent without permission will be deleted."