I’m working now for over 15 years in information technology, but i got never before a server response which is so straight and funny too:

The server is unwilling to process the request.

Maybee the server could do it, but he doesn’t like it. The error above was caused by this simple vb-script, when user Test-User has the group Domain Users defined as primary group:

Set objDomainUsers = GetObject("LDAP://cn=Domain Users,cn=Users,dc=domain,dc=local")
objDomainUsers.Remove("LDAP://CN=Test-User,cn=Users,DC=domain,DC=local")