LabView interface with DLL that uses ActiveX

Question

I've written a DLL using Microsoft Visual Studio 2005. This DLL uses ActiveX (MSXML4.0). It works fine being called from other applications created in Microsoft Visual Studio. It crashes being called from LabView 7.1. By commenting out everything, I've figured out that it crashes on the call to ActiveX (no problems if this call is commented out). What should I do to make it work?
I've tried using CoInitialize at the initialization of DLL; it didn't solve the problem.
Additional information: DLL is using MFC in a Static Library, not using ATL, Character set = Not Set.
The functions are defined in C calling convention (not __stdcall).
Please help.
Thank you.
Irina Kaliniouk

Answer 1

Thank you for your answer, but that is not the case. There is no UI in this DLL, but it is using some convinenient MFC classes, like threads, CString, etc. The threading really was not even involved in the example that crashed. The function that crashed was
selectNodes on MSXML2::IXMLDOMNodePtr. Here is the code:
MSXML2::IXMLDOMNodeListPtr selectNodes (LPCTSTR expression, MSXML2::IXMLDOMNodePtr pStartNode)
CComBSTR quesryBstr (expression);
return pStartNode->selectNodes (quesryBstr.m_str); //_bstr_t(expression));
where the pStartNode was a root node of
MSXML2::IXMLDOMDocument2Ptr m_pXMLDoc;
hr = m_pXMLDoc.CreateInstance ("Msxml2.DOMDocument.4.0", NULL, CLSCTX_INPROC_SERVER);
I commented out really everything except this function, so there was nothing to corrupt the memory or any other problems.  
What can be of a problem?
Thanks.