Sigh. I had copied all of my music to mp3s for Flex, but I tried a few albums as hi-rez, and Flex seemed to work, so I changed Flex to look for my music in the HD folders. After numerous playback errors, I switched back to the mp3s, and the above error mostly-almost completely went away. So I guess the issue is moot, since I listen to Flex on my TV surround systems, which aren’t HD, so I’m not going to try to fix the errors I got with the HD files. Thanks for the suggestion, if the problem recurs I’ll check the filenames.