Non-magnetohydrodynamic effects, caused by a minority population of energetic particles and/ or by the large gyroradii of the main ion population, strongly modify the stability of a high temperature toroidal plasma against m = 1 internal modes. We show that the enhanced stability due to the presence of the energetic particles is reduced in the large gyroradius regime, where the width of the transition layer of the mode is determined by the gyroradius of main ions. This modification results from the presence of a discrete spectrum of resistively damped Alfven-type modes which can be destabilised through the resonance with the energetic ions.