Problem traced to FSDT.
Per instructions on this site:
http://forum.simflight.com/topic/683...rst-installed/ I deleted the dll.xml in the fsx-cfg folder.
Sim started ok and closed ok, sceneries appeared ok except those by FSDT, they missed the buildings (a known issue, had it before and had to reinstall any 1 scenery to generate a new coarlf-something add-on manager).
I now reinstalled the scenery (any 1), which generated a new dll.xml, started the sim and it crashed.
Deleted the dll.xml, sim started but FSDT sceneries had no buildings. And this went in cycles... ->
1. Installing a scenery => crash on start up.
2. Removing the dll.xml => sim starts and closes but FSDT sceneries have no buildings.
3. Unistalling the sceneries => sim starts and closes but no FSDT sceneries.
I have all USA-FSDT sceneries and fly between these mainly, plus FlightBeam, FlyTampa and LatinVFR KMIA, so giving up on FSDT is not an option.
An option-2 is to reinstall FSX with all add-ons, something I really want to avoid doing due to lack of time and patience it would take.
An option-3 (preferred option) is you guys helping me with this.