IWordBreaker Implementation in C# causes MemoryAccessViolation

I have inherited some code that makes开发者_StackOverflow use of the Windows IWordBreaker and IWordSink interfaces. There is an issue when multiple threads execute and use this code (to break multiple documents concurrently) - The IWordBreaker.BreakText() method throws a MemoryAccessViolation error.

Does anyone know how to use this type of Exception to get to the root cause of the error?

Also - Documentation on these interfaces and how to use them within C# appears to be rare. Does anyone know of any good sites, books, or other material that would help me understand these interfaces better?

Many Thanks,

Paul