Thank you for your response.
I deleted my previous version and did a clean install of version 10.50. Problem persists
I'm flying the C172 from KVUO, daylight with overcast skies. Altimeter reads correct field elevation of 28 ft MSL when instrument panel view first appears
Problems start when I go to the Environment/Weather page to reduce low-level cloud base to 700 ft. On returning to the instrument panel view, altimeter reads 72,660 ft. When I dial altimeter back to the field elevation of 28 ft MSL, program locks up. Thanks for your help.