Okay.. I went into emplode and nuked most of my (rather large) custom playlists, sync'd, and..

The player locked up solid afterwards.

So, power-cycled, and now.. no more jitters (so far).

I'll try re-adding my playlists again now.

UPDATE: my (huge) custom playlists are back in,
and the player is (so far) jitter free. Go Figure.