AFAIK, Firefly does not support any DRM protected music.
Firefly may be choking on the old database entry for this track.
Even though you've shortened the name, there is still a db entry for the old name.
Try deleting the db file and have Firefly build a new one from scratch.
The database will be named songs.db or songs3.db
2 x M2000's
Infrant ReadyNAS NV+ with Firefly svn-1676
NSLU2, 500GB Maxtor One Touch III, uNSLUng 6.8, Firefly svn-1696
music library in FLAC format