OK, here's another update on the filename importing thing. I had a folder of lots of Christmas Carols thrown together from various free CDs, which had filenames like "01 Once in Royal David's City.mp3", "01 Away in a Manger.mp3", "01 Silent Night.mp3", "02 Good King Wenceslas.mp3" etc, and although Import From USB imported them all onto the hard disk as viewed from the computer, the Web UI and the front panel display could see only one mp3 starting "01 ", one mp3 starting "02 " and so on.
Scan Disk, which seems to fix everything else, did not fix this.
I've now renamed the files to fix the problem, but this seems like an anomaly (or maybe a bug).
Dick Cooper