Client access licenses disappeating on SBS2003

[toksoladuti]

We have a single SBS 2003 domain controller on our network with 15 CALs in total. Every now and then users are unable to log in and upon checking the licensing I find that the additional licenses have disappeared and it defaulted back to the five minimum. I then have to restore the licenses from a back-up. In the Event Log I see several culprit entries whic are as follows:

Source: SBCore
Event ID: 1017
"The license store for the client access licenses was corrupt and had to be deleted."

Source: SBCore
Event ID: 1009
"The license store for the client access licenses is not valid and could not be restored from an automatic backup. Only the minimum number of client access licenses will be available until a valid license store is restored. For more information, see Help in the Licensing snap-in."

Source: SBCore
Event ID: 1023
"The license store for the client access licenses is not valid. Only the minimum number of client access licenses will be available until a valid license store is restored. For more information, see Help in the Licensing snap-in."

Source: SBCore
Event ID: 1016
"A new license store for the client access licenses was created."

Can anyone help. Many thanks.