Drift instabilities arising when accelerated protons are trapped by coronal magnetic fields of active regions are investigated theoretically. If β, the ratio of total (plasma + energetic particles) pressure and magnetic field pressure is larger than some value, β⋍0.1 to 0.3, the magnetic trap is destructed and protons are released into interplanetary space. If β < β ∗, the trapped protons excite gradient instability due to magnetic drift resonance. This “universal” instability results in rapid development of strong Alfvén wave turbulence with small wavelengths transverse to the magnetic field. Particle diffusion due to the waves has a rather complicated character and appears to be weak as compared to quasilinear diffusion. The role of Alfvén waves may consist in additional heating of the corona in the regions of closed magnetic field lines.