Compressor v4.1.3: can't create mpeg2 movie: Error: This Is Null

Using Compressor 4.1.3 and FCPX 10.1.4, I attempt to use compressor to create a MPEG2 movie using the "MPEG2 Program Stream, 15mpbs" option. I was successful once, the first time. But I had a problem with that video in that the audio would play but the video would freeze. So any attempt since then fails with the following error:

Failed 3x Host: [macbook]: Error: this is null.

I don't change any of the video default options. Just using all of the default options presented to me. And it fails.

Seems like a bug in compressor since I'm not changing any options.

Any idea what the problem might be, or how I can create MPEG2 movies using compressor?

Thanks, Jim