I believe that what happened is your Sub Expire Time expired. If you go to the Ceton Diagnostic page (192.168.200.1 by default) in your browser, click on CableCARD, click on the CA link and then click on the link on the page that comes up, you will see “SubExpireTime” and a time/date.
What happens is the cable provider sends a message to the CableCARD on some periodic basis (or is supposed to). If the CableCARD doesn’t receive the message and the time passes the “SubExpireTime,” you will receive Subscription Required overlay in WMC.
