Please provide more details.
For instance, when you boot to the install DVD, did you get to Reset Password Utility and reset the password successfully?
For instance, when you restart and enter your new password into the login window, what happens? Does it shake? Does it disappear?
For instance, when the new HDD was installed, did you install the OS or did the ARS? If the ARS installed, then have you tried doing your own clean install, a.k.a. an erase and install? Or have you migrated your data over from the previous HDD to the new one by way of a Time Machine backup?
The more details you provide, the better we can assist you.