Having this problem too (NTDLL.DLL CTD). Not Overclocking (don't even know how.) constant CTD's just migrated from FSX to P3DV3 this weekend. Tried installing the newest add-on manager as read in another forum. Running REX 4 Texture Direct, REX Soft Clouds, ASN SP5, and PMDG 737-700NGX; Would love to complete a flight!
Faulting application name: Prepar3D.exe, version: 3.3.5.17625, time stamp: 0x5758bb31
Faulting module name: ntdll.dll, version: 6.3.9600.18233, time stamp: 0x56bb4e1d
Exception code: 0xc0000374
Fault offset: 0x000e6054
Faulting process id: 0x6e4
Faulting application start time: 0x01d1dacfef3f9cf6
Faulting application path: C:\Program Files (x86)\Lockheed Martin\Prepar3D v3\Prepar3D.exe
Faulting module path: C:\WINDOWS\SYSTEM32\ntdll.dll
Report Id: 0e20c9b4-46c5-11e6-bfed-240a64036ec0
Faulting package full name:
Faulting package-relative application ID: