Solved, sort of. I posted the problem to the programmer's github acct. The programmer was not sure of the cause. I decided to try the Win 10 Universal Remedy: right click and Run As Administrator. The program seems to be running fine in this mode.
Does anybody know how to get Little Navmap to show FSX:SE airports? I downloaded and ran Little Navmap. But it's not showing airports. At the bottom, it says "Connected (FSX/P3D)" and "Database empty." In the "Scenery Library" menu, there is a "Load Scenery Libary" dialog, but the simulator drop down lists only "X-Plane 11". I have the "Show airports" buttons on. I do see NDBs and VORs. Where are the airports?