This is an issue that keeps tripping me up in the development lab.
I create a quick database, and then after some time I go back to try to log in, and get:
ERROR: ORA-28002: the password will expire within 7 days
And then I spend a while trying to figure out how to disable the password expiry component of the profile.
Here then, for my benefit as much as anyone else, is my quick guide to checking the user profile, and then disabling security components that cause headaches in the development lab.