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The hostile crazy mage you un-imprison from the weird machine in the Underdark can be cured with the heal spell, as well. (Not the lich)Minsc is not insane. He is ENLIGHTENED.
Sadly, it does not seem to work on Minsc, (other than fully healing his hp) no matter how many times you may try. Nor on the poor inmates in Spellhold. It seems the damage is too old/chronic in their case and have been made permanent.