How to generate a heap corruption from VB6

We have a C# windows service that call vb6 functions and one of our customer has sometime this service that crashed with 0xc0000374 error on ntdll.dll (Heap Corruption Exception).

It's impossible for us to reproduce their problem, and in order to learn how windbg works and how debug this exception, how can I generate the same error with a piece of VB6 code ?

It would allow me to see how could I debug this kind of error and make the same things at my client site.

Thank you for your help