IIS 3.0 Password Problem

I have IIS 3.0 running on a NT 4.0 server. I have a virtual drive setup w/a password to sign on the another drive. My question is. Why does the password change when I reboot my server. After a reboot I have to go back in and change the password backor it does not work. By the way I have tried making the password blank and it still does not work.