Greetings!

If you have the developer version loaded, you can drop to shell and:

rw
rwm
cd /drive0/var
rm database*
rm tags
rm playlist*
player

Note: Running the player from shell like this without the database files there will force the player to rebuild them. With the drives read/write will allow the player to save the files back to /drive0/var. After the player application is loaded, type "q" to exit back to shell. It should reset the drives to read only, but just in case...

rom
ro
exit and reboot.

Try your sync now.