More on this behavior. I've been trying different patterns, sequences and options up to the point of conversion, various dsp settings, etc., and when it's acting flaky it's hit and miss. Meaning, in a group of 9 songs, it may process each of them correctly, it may process the first 4 correctly and the rest corrupted, or it may corrupt all of them. Sometimes you can do just one, get a good conversion, do it again and get a corrupted version, with no changes in between!
I was trying to find a combination of options that would set it off, and at first it seemed like turning dsp on/off would break a current trend, then it seemed like bit rate between 24 and auto would make a difference, then this, then that. This is also after having re-run it and the server several times, which never seemed to make a difference. Except one time it crashed (MC and the server, not just MC), when it came back up after that, everything began working correctly (no corrupted files) for five complete sets of nine tracks each, even with different options set.
Of note is the fact that in those five sets of 9 uncorrupted conversions each, no set of five track #x's have the same filesize... Here's an extract of four of the five sets of filenames and sizes. I'm not sure if it means anything, but you'd think they'd be the same if the options were the same. In these, the unnumbered track and (1) track were done with the same options, while the (2) and (3) tracks were identical except that DSP Apply Volume was enabled.