So I just had a member who said they were going to leave because they could do anything at the site. I found that to be weird and looked at the user in the Accounts module and saw a red Lock next to their name.
Why would there be a lock there? What did the user do in order to become locked?
Account is locked after 6 login attempts, when password isn't entered correctly several times. User can use Forgot Password to unlock their account. Also site admin can unlock accounts from accounts administration page.
You can change this setting in Studio > Settings > System > Account > Max number of logins attempts (0 - no limit)