I am also having a similar problem. Say I drag 80 songs into a playlist, and hit sync. it goes through all the motions, only very fast. It thinks it's complete, but alas, nothing has changed on my player. I am running 2.0 final /w Hijack 340. Also running is emphatic, running on a non - music partition. (Hence no errors on disk integrety check). Oh, I cannot even delete a song. (well, I can, but not if I use the playlists tree. If I used all tracks, it allowed me to delete. Tres bizarre.
I also noticed some bizarre behavior this morning. I was playing a Zeppelin tune I've played a thousand times before and it started to skip. Badly. I hit next, and that song was skipping too. I yanked the player out and slid it back in, all booted and started playing smoothly with no problem. I then wanted to see if emphatic was causing the problem, so I launched it. Then all my keypresses stopped responding except for pause. Very strange.