I am assuming that you are using a dual-tuner adapter. If so, then it is possible that one of the tuners in your adapter went bad. By default, recordings are done on Tuner 2, and Tuner 1 is used for Live TV. If you try recording two OTA shows at the same time, the timer with higher priority will go to Tuner 2. So, you could try recording two OTA shows at the same time, and see if only the one with the higher priority in the Timers list has the problem, or if both recordings end up being unwatchable.