Multi-site problems: redirection and error creating user


- I created a multi-site network
- I installer the multi-site plugin

my main website is

- I've added two sites:

I know they must exist because I can browse the wp-admin, but the websites don't load.

What can I do?

Problem number 2

Now, when I try to create more sites, i get this:

There was an error creating the user.