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