Acct kept locking up by itself

Check to make sure there is not an expire time set for the account in User Manager. Even when you "unlock" an account, if the expire field is active it will disable to account again.

You may be logged into another machine in your network. If this is the case and your password has changed, a process from that machine to the server will try to authenticate with your old credential which consequently results in the lockout after anumber of unsuccessful tries depending on account policy settings.

I experienced this recently and as soon as that machine was located and turned off, the problem was resolved.

Goodluck.