Reality GNT650 blank or 'Reloading...'

I've had that problem with all aircrafts, but recently I added vFlyteAir Arrow III that works with Reality XP (on the panel AND as a pop up) and I'm experiencing this problem: the GNT650 starts VERY randomly: sometimes it fires up, but more often it remains dark, or remains dark with a small message at the lower left corner saying "Reloading...", only nothing happens. Of course, 9 out of 10 times switching a/c results in the entire X-Plane crashing, but this issue is most likely unrelated.