Glitch with Great Balls of Fire

I've used the secret path at the entrance of the Oracle section and am in the middle tower of the three. Going east from the first map to the next; just above the entrance is an Ohr. When I try to use Calypso's Great Balls of Fire against it, I get an error message, and her spell is aborted, as is Jardel's turn. The game continues, but I have to use physical to finish the fight.