Home Theater

Cox informed me that my cable box was outdated and would no longer be supported earlier this year so I switched to their newer version. Ever since I changed cable boxes my video no longer comes through on my projector/theater system. DVD and games work fine so I know it's not the projector. Sounds come through but no picture.

AV Receiver is an Onkyo TX-NR525. No firmware updates were available for the receiver. Any ideas would greatly appreciated!