First thing I would do is contact Cox and see if they still support cable cards in your area. I hear it was only a matter of time since Comcast and a few other ISP have already quit support. On the Cox CC support page, it says;
"Due to the evolving use of the Internet to view and transmit video programming, Cox must make network upgrades to ensure its programming remains secure. It may be necessary to contact the equipment provider for Cable CARD-ready devices to upgrade your device."
I read a couple posts about that is the error people started getting when the system shut down.
Second, Do you have the new tuner adapter? It's considered a high-split tuner adapter but I forget the manufacture. Begins with an "A". I know that it is needed in areas with 2Gbps service or that are considered mid-split. That would usually only cause a problem with premium and SDV channels, not all channels, so I think it may be the first thing. Fingers crossed for you.