The last couple of weeks there is a spam bot that has "detected" our site. This has resulted in some user registrations and advertising topics. To prevent this from happening, I had to change the registration procedure so that all new users must be approved by admin before they can use the forum.
If you are a new user and have not been approved within 24 hours, then write to admin and request activation. I'm notified of a new registration, but if I'm in doubt it's a "real" user, I will not activate it. Rather safe than sorry