Help with exception "Attempted to read or write protected memory. This is often an indication that o

[EDN Admin]

 Hi
Ive been trying to figure this out for a while now without any success and decided its time to try a post. Basically, Im trying to call a function from an unmanaged C++ dll. It works fine the first few times, but after a few minutes, I get the following exception:
"Attempted to read or write protected memory. This is often an indication that other memory is corrupt."

Here are the details of the function:
C++ function:
int someFunction(
long some_handle,
const char* query,
char* queryResponse,
unsigned int& queryResponseLength,
unsigned int timeout
);

C# wrapper:
[DllImport(DLL_NAME, SetLastError = true)]
internal static extern int someFunction(
uint someHandle,
string query,
byte[] queryResponse,
ref uint queryResponseLength,
uint timeout
);
- Note that The queryResponse and queryResponseLength parameters are used as output parameters.

Ive tried using a StringBuilder for the queryResponse Attribute, several combinations of [MarshalAs] tags and also tried pinning the parameters, but Im not sure how correct Ive been in any of these approaches. Any help would be greatly appreciated.
Thanks in advance

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