I just had the same problem (last week) and the solution was to turn off all optimizations (in the project settings) for the dll. It worked for me, but I still don't know what was the real problem (or which optimization creates the problem) because I had no time to look at it closer. Please let me know if you find more details about it.

Vlad

>I have created an MFC DLL with some objects that I use in other programs. I created the DLL with the wizard in Visual C++ 5.0, and then declared by objects like the following:
>
>class AFX_EXT_CLASS CClientReg : public CDGMsg
>{
>// Constructors
>public:
> CClientReg();
> CClientReg (const char *chpClientName, struct sockaddr_in ClientIP,
> const char *chpRCList);
> virtual ~CClientReg();
>
>// Attributes
>public:
>
> CString m_strClientName; // name of the client application
> struct sockaddr_in m_ClientIP;// IP address of the client's stream socket
> // int m_nRCCount; // number of routing codes in the list
> CString m_strRCList; // list of routing codes handled by client
>
>// Operations
>public:
> virtual bool load(); // put the member data into a buffer for sending
>
>};
>
>I can declare objects of this type in my other apps just fine, and the constructors work OK. However, if I try to set the value of one of the string members using the CString operator '=', or using the Format method, I get a "user breakpoint" message (I don't have any breakpoints set), and the TRACE window shows me this:
>HEAP[callctrl.exe]: Invalid Address specified to RtlFreeHeap( d40000, 5f4c0b90 )
>and the program crashes.
>Shouldn't I be able to do something like:
> CClientReg regMsg; // this works OK
> regMsg.m_strClientName = _T("Client One"); // this crashes
>
>Also, the program runs fine when compiled in 'Debug' mode. It only breaks when running in release mode.
>
>Any ideas?
>Thanks