I finally got mine working. Had to redownload and install to default location. Luckily I recently installed new 1TB SSD as C:// drive.

Turns out my original download included 4 base scenery .bgls that were so corrupted that I can't delete them!?? I also can't overwrite them, so the entire folder structure is trapped. Anyway, the sim is working well for me now, in default form. Aircraft and scenery bought from the store are working fine. next is to try my ORBX scenery and Dino's Longeze, as well as IRIS' Jabiru.