Hi there The line 622 in atlbase.h is the -> operator of the CComQIPtr< > class template, and I don't see you are using any instance of it in the code you posted, so I suggest you to open the "Call stack" (Alt + 7) when you get the assert, and follow you way up until you reach the line in your code which is calling the -> operator on an instance of CComQIPtr<>, and then take a look why that pointer is NULL. Regards, Fabian