My program was terminating with no runtime error message. When run in gdb, gdb told me it terminated with exit code 52 (I think octal).
I had a Range Check Error. In gdb, I see that _p_RangeCheckError calls _p_RuntimeError. Then, _p_RuntimeError has code that might call _p_RangeCheckError. I didn't trace further -- gdb suddenly becomes unable to single-step, says "Unable to set breakpoint number -37". (The specific number changes if I keep trying to single-step. It's always negative.)
I don't know how much better it would have been, but shouldn't _p_RuntimeError have been compiled with range checking suppressed?
(I've found source for RangeCheckError and RuntimeError. I can't find source for CString2String -- is it an intrinsic function? It seems to have been inline coded in RuntimeError.)