I have been using QTB to broadcast and simultaneously record live events, each of which last about one hour.
I am using QTB installed on a Mac mini. An Elgato Turbo.264 HD device is used for encoding.
Video feed is from my Panasonic AGDVC30 camera. Audio is input from the microphone feed.

Most of the time this works without problem. But intermittently, for no apparent reason I find that the video feed "freezes" and that last frozen video frame is both recorded and broadcast in place of live video. The audio continues to be broadcast and recorded just fine. So as a final movie product I often have a few seconds or minutes of audio and video followed by nearly an hours worth of audio superimposed on a static image. Once the live video is lost it does not begin again. But if I stop the broadcast and restart it for additional broadcasting/recording it often will work fine again. It is a very intermittent problem.

I need help determining what is likely to be the cause of the loss of live video. Do I have my video broadcast parameters set too high? Am I overwhelming the processors in my Mac mini? Is this a problem with the video camera itself? I don't even know where to start to troubleshoot this problem.
Any help is greatly appreciated.
John