I have figured out how to crash the program. Well not figured out but did it 2 times in a row. Pretty sure it's related to infill.
Program "drops" after I try "prepare to print". - Just vanishes. No error on screen.
Will update this original post as I worm out the details.
Faulting application name: Simplify3D.exe, version: 5.1.2.0, time stamp: 0x64d66988
Faulting module name: Simplify3D.exe, version: 5.1.2.0, time stamp: 0x64d66988
Exception code: 0xc0000005
Fault offset: 0x000000000024a207
Faulting process id: 0x4708
Faulting application start time: 0x01da196353e7ca75
Faulting application path: F:\Simplify3D-5.1.2\Simplify3D.exe
Faulting module path: F:\Simplify3D-5.1.2\Simplify3D.exe
Report Id: 1ac42347-f752-4632-bc51-599392660793
Faulting package full name:
Faulting package-relative application ID:
Source: Application Error
Task Category: (100)
Event ID: 1000
Level: Error