[jeremiah82]

Ok, for now i have this solution:

bp-core-wpabstraction.php

$maybe = array();

preg_match( "/^[A-Za-z0-9_-]*[A-Za-z0-9_.s-]+/", $user_name, $maybe);

// preg_match( "/[a-z0-9]+/", $user_name, $maybe );

$illegal_names = get_site_option( "illegal_names" );

I changed the preg_match record to another regexpr. It works for now. I hope there is someone who can tell why i shouldn’t do that.