So far SD has worked well on the PC. Today I noticed a strange behaviour: on larger scales than 1:1,000,000 (e.g.. 1.900,000), a lot of aeronautical detail vanishes and a big red X is drawn across the entire map. Zooming out beyond the 1:100,000,000 mark and the X disappears. However, at these scales some aeronautical detail is suppressed also because of the zoom level.

This problem has occurred out of the blue. I didn't update SD. I tried to fix this by updating the maps but that didn't help either.

Thanks for the help, --Chris.