New users' password not working

Hello !

I’m using WP 3.0 installed as a multi-site.

When users register, they get an email with the auto-generated password. But when they try to log in, they are informed that they don’t have enough permissions to log in.

Afer clicking on Log In, in the adress bar, the url becomes /wp-admin/?c=1, then /wp-admin/?c=2, /wp-admin/?c=3, /wp-admin/?c=4 and /wp-admin/?c=5. Then the error message is displayed.

In the backoffice, the user is created but is not linked to any blog. I guess that explains why they get the error message (they don’t have permission to log in the root blog).

Anyone has ever experienced this problem ? Where should I look for to solve this issue ?

Thanks for your help !