If an account keeps getting locked out whether its on a local computer or a domain controller (depending on the type of network the machine is on). There are some basic steps you can follow to try to troubleshoot the lockout issue. One of the first places to start is to search the event logs on the local computer or a domain controller for account lockout problems.
Below is a list of common problems that can cause an account to get locked out:
Note: This problems can also be caused by badly configured security policies on a large network.