I think your best solution to OOM's/CTD's was the link you provided to the Microsoft fix to enlarge the heap and I thank you for that!
I don't use an anti-virus program, never have since 1991, never will (well okay, I did once back in the 1990's but just long enough to see if I had a virus). I do have the Windows Firewall enabled and I do safe-surfing. In other words, I don't download or install anything unless I know the Source. I know FSDT, FlightOne, Aerosoft, and SimConnect, PC Aviator, etc., are reliable. They have very good security systems that make purchasing things very safe. I run a malware detection program at least weekly (i.e., Super Anti-SpyWare and Advanced Systems Program) and recommend others do the same at least weekly. One should not rely solely on any anti-virus program installed to save them from a major disaster. New viruses are discovered daily and, by the time an anti-virus program developer knew of the virus and issued new definitions, a persons computer could be destroyed. It is good for known viruses. As I stated, I have never turned off DEP and never had the problems related in the links you provided in Post #9. Most of the BEX/StackHash CTD's I have seen in these forums have been caused by a bad install of an fsx addon or, like in my case, it was something stuck in memory that many others with multiple monitors suffer from occasionally. FSX remembers whether you open/close FSX in Windowed or Full Screen and it gets confused when you do the opposite of what FSX expected to happen. It is easily fixed by opening/closing FSX in windowed mode and never closing in full screen mode.
The links you provided in post #9 are dated but from reputable Sources. Security has changed a lot since 2008 and I think developers working with security for their products are aware that turning off DEP in FSX is not allowed so they have developed it so that it does work properly. It is to their advantage and profitability that the product and security work properly. That's all I have to say. Thanks again for your excellent info and insights into the world of FSX CTD's.