Passive Login Issue

[nottinghub]

We are running FS v7.0.6 on Windows Server 2008 64-bit and mySql v6.

our current login option include "Both Username/Password and Scratch Code together". We don't use shopping cart in our setup. So "Redirect to shopping cart when user fails to login" is set to "No".

Whenever I create a user with the following parameters:
username: testuser
type: Normal (username/password)
password: testpassword
Account is active: now
Bind to first login MAC address: Yes(login once - set as Passive Login after first login)
Free Access User: Yes

Testuser is able to login and go online. From that time onwards, when I look up that user in the "configuration manager> users" screen, I can see the username changes to "testuser(XX-XX-xx-xx-xx-xx)" where XX-XX-xx-xx-xx-xx is the MAC address of the user.

A few days later (when FirstSpot has restarted at least once), when the user goes online, he gets the following message: "User has no usage time left" without being presented a login page, and connect go online.

Any idea what should I do?