Wierd PMM problem

[Genesis]

I have put a big (120gb) drive in my Phatbox.

Suddenly, when I sync/rebuild the cartridge, albums are all screwed up.  The order on the head unit is NOT alphabetical, and when I select an album often some songs are either missing or what plays is not from that album!

Looking at it on the PC its correct - but in the car, its not.

Any ideas?  Playlists seem to work ok......