Greetings!

Some questions, in order:

a) Are you running the developer kernel? 2.0?
b) If so, go into shell. Do you have anything in /drive0/fids and /drive1/fids (if dual disk)?
c) If so, you might be able to manually rebuild the databases by:
rw
rwm
player
(quit the player application after it finishes loading - it will take a while to rebuild the database, playlists and tags files)
rom
ro
exit
reboot, resync
d) If /drive0/fids is EMPTY, there is something nasty going on, and it will need a bit more effort.