I was testing out Dolby Digital 5.1 using my new 20' TOSLINK cable when all of the sudden the screen went blank. I freaked out! It was seven days after my warranty expired!
Fortunately, I discovered that my S-Video cable had wiggled out of my video scaler during the jostling just enough that it lost the signal. I plugged it back in and all was fine with the world.
Triple heart attack: Averted.