I'll put it on the list of things to do. *sigh*

Have you tried this yet? Basically, something on the player (and as there's no 3rd-party stuff installed it must be our player software) is holding open a file on the music partition, which means the media check can't go ahead. The most likely type of bug that would cause this, would be some kind of bug in the database loading such that it failed, but left the file open. Renaming all three database files (database, tags, playlists) out of the way and rebooting, so that the player isn't loading any database files but is rebuilding the database on startup, would fix the problem if this is the case.

If, after doing this renaming, you can successfully synchronise, I'd like to see the original database files that caused the problem. If, after doing the renaming, you can successfully synchronise once and then the problem comes back, I'd like to see the new database files too!

Sorry I haven't got back to you until now, but we're all (a) very busy and (b) stumped!

Peter