I have noticed that when I move from one chart to an adjoining chart, I get a red flashing screen and the warning "GPS reception lost". This was particularly noticeable when going into a Canadian chart which of course there are none in the database. Going from Seattle to Prudhoe Bay Alaska I was in and out of Canadian charts quite a few times. I had to unplug the power and reboot. The the magenta direct line would then show on the blank Canadian chart.