Sudden loss of headphone audio.

So, I was watching a show on my tv, with audio and video input coming from my computer via HDMI. I was listening over my headphones (which were plugged into the receiver to be clear), but I suddenly lost all headphone audio. This was not computer software related, as audio still comes through my bookshelf speakers, on all channels that I have an input (i.e. CD, Video 1, DVR1). However, I do not have any audio through my headphones on any of those various inputs.

There is no static or distorted signal. Just a heaping serving of nothing.