systems stopped updating and showing as un-entitled

[Tom H]

Hi,

I have some redhat boxes that are using redhat networks for updates, and
they have all stopped updating together and are now showing as un-entitled;

Error Class Info:
     This system does not have a valid entitlement for Red Hat Network.
     Please visit https://rhn.redhat.com/rhn/systems/SystemEntitlements.do
     or login at https://rhn.redhat.com, and from the "Your RHN" tab,
     select "Subscription Management" to enable RHN service for this system.


Any ideas what is going on, if I try to edit them to change them to
entitled. Nothing happens.

Thanks,

T