Big login problem

I’ve some members who have this error when they tried to login to my site:

We apologize for the inconvenience but your WordPress Login page has been temporarily disabled. You are seeing this page as your site has recently been the target of a brute-force attack attempting to gain access to your WordPress Dashboard. In order to secure your site and prevent attackers from gaining access to your data, you will be unable to login to the Dashboard until the block expires. For more information please see our support site

& sometime this one too:
Error 403 – Forbidden

You don’t have permission to access the requested resource. Please contact the web site owner for further assistance.

I didn’t play with anything on my site, I know that wordpress have hacker who try to hack their platform or whatever, but installed the latest s2member update, the login for me work perfect and some members can have access too…

I really don’t know what’s the problem and my host can’t help me, they said the problem is from the plugin… They repair the permission and it’s not working..
Please help, every hour I lost money from members who want to have access and it’s important for me to give the best service I can.
Thank you

You can find the Brute Force protection settings here: [hilite path]Dashboard -› s2Member® -› Restriction Options -› Brute Force IP/Login Restrictions[/hilite]

Regarding the 403, please see if this is related: Knowledge Base » Mod Security, Random 503/403 Errors