I hope by now you've gotten an answer but I just came across your question so if you've not ... Check that the TV tuner has not come loose from it's connection. It normally only affects mine in really hot weather but the tuner box they added to an aux input loses it's connection and the TV option disappears from the menu and a NO PC SIGNAL alert appears. Most often unplugging the adapter FROM THE TV ITSELF and then plugging it back in solves my problem but sometimes I need to take the tuner compartment cover off and assure the tuner is tight to the aux input. If you try disconnecting the adapter first IT MUST BE DISCONNECTED FROM THE TV ITSELF as the adapter holds a charge for a short period of time so unplugging from the wall doesn't have the same effect. Hope this helps if nobody else has already responded with something that resolved your situation.
