By the way, please tell Algolei that he should *never* post his password on your message board (or anywhere, for that matter). It is just begging for trouble.
Once he's able to log in again, have him change it to something more easily remembered (but not too easy!).
Even if the cookie gets deleted, there's no harm done, as a new one gets generated as soon as a user logs in again. History files incidentally are simply internet addresses of recently visited websites and when they are deleted, either manually or automatically according to your setting, only they get deleted and not any cookies.
Edit: Just in case you're wondering, the post just above mine by "Algolei" was BbAdmin logging in as him to demonstrate that the password is working OK.