It could be a number of issues to be honest. I would suggest these steps to see if it's a hardware issue. First make sure there are no loose wires. If that's ok then try plugs the cable box hdmi into a different hdmi port. This will rule out of there is a bad port on the tv. If that's fine then try a different hdmi cable if you have one laying around or swap with another device. This will rule out a bad cable. Finally if those didn't work try to swap the cable box with another if you have two or try on maybe a bedroom tv if the issue happens frequently enough. I have seen many faulty cable boxes over time. If all that checks out it could possibly be a setting of sorts either on the tv or cable box. When I set mine up though I did not make any settings changes that should affect a signal loss.