From discussions on other lists, and my own experiences, I have discovered
the following things:
1) Bard songs will cause creatures to see through invisibility, sometimes
even cancel it.
2) Bard songs will bring someone out of hiding if they are in your group.
3) Bard songs can break root and whirl spells - even if you aren't using
offensive ones.
In other words - Bard songs are major conflictors with other spell effects
in the game.
Talies on Bristlebane
http://amtgard.pinkpig.com/bards/eqbard.htm