How to get information on a Buffer Overflow Exception in a mixed application?
The .NET 4 version of the CLR has protection against buffer overflow attacks. The basic scheme is that the code writes a "cookie" at the end of an array or stack frame, then checks later if that cookie still has the original value. If it has changed, the runtime assumes that malware has compromised the program state and immediately aborts the program. This kind of abort does not go through the usual unhandled exception mechanism, that would be too exploitable.
The odds that your program is really being attacked are small of course. Much more likely is that your native code has a pointer bug and scribbles junk into a CLR structure or stack frame. Debugging that isn't easy, the damage is usually done well before the crash. One approach is to comment out code until the crash disappears.