Managed Code Calling Naïve code

I have a project where managed code calls a naïve code program, which in turns call another naïve code program.  I get a stack overflow on a read after processing about 300 records, it's a basic read/generate report program.  This managed code project, has about 47 naïve code programs in it.  If I run just the naïve code, .exe program calling the report program, it runs fine.  Suggestions?