You should contact your hosting company - this issue may be related to recent massive attacks on servers hosting WP sites - see:
http://wordpress.org/support/topic/brute-force-attacks-and-wordpress?replies=2
You should contact your hosting company - this issue may be related to recent massive attacks on servers hosting WP sites - see:
http://wordpress.org/support/topic/brute-force-attacks-and-wordpress?replies=2