Registering Problems

Hey guys,

I have a phpBB3 Forums and whenever one of my friends attempts to create an account on the forums, it says every username possible is taken, such as sgdgsdg, How can I fix this problem? All help is appreciated thank you.

General>Forum Security
Unauthorize subscriptions made with the most commonly used spam usernames. : No
Save
That will change the problem, but beware that it opens a whole gateway for registration made by spam names.