Since I installed 5.4c, I have been having ntll.dll crashes very frequently in any airplane (default C172 and no weather to 737NGX with REX Wx engine) Before 5.4c, I was running 5.4b at 35% airline and 20% GA, and 100% UT2, and never had a crash. I did a bunch of trial and error, and finally narrowed it down to MyTraffic. Once I disabled it in the scenery library, I no longer had ntdll.dll crashes (even after slewing around the world at 40,000kts for hours). I even used settings such as 10% Airline and it still ntdll.dll crashes.
As an example, last weekend I did KPHX-KORD-