Can you please elaborate? Are you claiming that Mint locks you out? You're entering your password, however, you cannot log in? You should be able to reset your password by booting Mint in recovery mode (be careful!!! This is a root shell!!!) Type the following:
passwd <username> (enter a password)
You should be able to log in normally.
You shouldn't have to re-install the operating system just because you're locked out of your system. That's like a doctor shooting the patient to cure his disease. LOL!