When you check the Smart card is required for interactive logon box for a user account, Windows Server 2003 assigns a random complex password.
When a network resource requires username and password authentication, the user cannot use the net use command to enter their credentials.
To workaround this behavior, use the /smartcard switch with the net use command. This switch will pass the credentials after the user enters their smart card personal identification number (PIN) in response to a prompt.
NOTE: An administrator can reset the user password, but doing so can compromise security.