Our G496 will freeze pretty much every time we pass the Rampisham HIRTA < 3000' < 5 miles (BBC world service). The screen locks up and the only way to restore it is to remove the battery to reset it. Took us ages to figure out what caused these lock ups and it was only when we noticed they were happening in the same place that we figured it out.
This is using a hull mounted antenna as well as aircraft power.