Computer supposed to display warning message at Logt In.

A customer of mine has a "public computer" to be used by many people.  As such it displays a warning message on Log In.

This is controlled from the Registry:

HKEY_LOCAL_MACHINE\software\microsoft\windows\Currentversion\Policies\System
on the right pane are two keys called LegalHeader and LegalText (forgive me if the spelling is slightly off).

This worked perfectly until today.  Namely the message would pop up just before the UserNames appeared.   EVEN if only after a log off'

Now the essage only appears after the computer  is re booted

Please Help!