I have an account lockout issue that is reproducible and exists across many devices.
These systems are Win 7 Professional 32-bit, not domain members, and fairly locked down via local Group Policy - I suspect the issue is in there, but I can't identify it. There are normally two administrator accounts (this might be important - see below) and one or more unprivileged user accounts.
To reproduce the issue, I log in to one of the admin accounts, create or delete a standard user through Control Panel>User Accounts, and then log off. Immediately both admin accounts are locked out. I can log in as the standard user I just created, but have to unlock the admin accounts by booting to DVD. The event log shows the admin account log off, followed immediately by 3 credential validation failures for the other admin account - that is, the account that was not logged in when the user management was performed. I can't imagine where these cred validation failures are coming from, but per Local Group Policy, 3 failures should indeed lock the account. Logs show no reason at all (AFAIK) for the first admin account - the one actually doing the user management - to be locked.
If I add or remove users through compmgmt.msc, there are no issues of any kind.