3004-303 There have been too many unsuccessful login attempts; please see the system administrator

If your user can’t login and is receiving this error message, you need to reset his unsuccessful login attemps in the user’s account.

Check his unsuccessful login counter with lsuser

root@aix:/ # /usr/sbin/lsuser -a unsuccessful_login_count <username>
username unsuccessful_login_count=4

Then reset the counter with chsec

root@aix:/ # /usr/bin/chsec -f /etc/security/lastlog -a unsuccessful_login_count=0 -s <username>