Hi all, How to create an Application which have a singleton class which herit form 3 other interface class (so with pure virtual functions), without loosing reference to these interface functions ? My problem is that I am lossing reference to vftable(__vfptr) between instances, so I cannot access to my interfaces in another instance of the application. More about this problem : 1 - I launch "MyClass.exe start" => OK "MyClass.exe" is running ... 2 - I launch "MyClass.exe configure" => access violation is raised, because can't access to MyClass->Configure(). NB: this problem not occur if I make -2- then -1- And although I call Configure() inside Start() it's working well. My implementation code is : #include "MyClass.h" #pragma data_seg("MyShared") MyClass* MyClass::m_instance = 0; // The MyClassUnique instance #pragma data_seg() #pragma comment(linker, "/section:MyShared,rws") int main(int argc, char *argv[]) { // Retrieve the MyClassUnique instance MyClass* Me= MyClass::Instance(); if(argc==2) { if(strcmp(argv[1],"start")==0) { MyClass->Start(); // OK MEMBER FUNCTION return 1; } if(strcmp(argv[1],"stop")==0) { C3STrace(C3S_TRACE_DEBUG, C3S_TRACE_INFO, "MAILNOTIFIER_STOP"); MyClass->Stop(); // OK MEMBER FUNCTION return 2; } if(strcmp(argv[1],"configure")==0) { MyClass->Configure(); // KO WHEN CALLED IN ANOTHER INSTANCE // Configure is one of the virtual function of one interface // I have an excetion acess violation at 0xXXXXXX reading 0xYYYYYY return 3; } } return 0; } ------------------------------------- class MyClass: public Interface1, public Interface2, public Interface3 { .... static MyClass m_instance; static MyClass* Instance(); virtual void Configure(); } ------------------------------------- MyClass* MyClass::Instance() { if( m_instance == NULL ) m_instance = new MyClass(); return m_instance; } -------------------------------------- void MyClass::Configure() { // do configuration job } -------------------------------------- Regards, Olivier.