this error means a pure virtual function wich is called a pure virtual function is a pointer to a function in this case it is not assigned to a function (i think) and then its called and gives error. i dont like errors like these(who doesnt hate Microsoft, CRT) instead of doing. if(v_ptr == 0) throw(exception); v_ptr(); they could do if(v_ptr != 0) v_ptr(); but its handy in debugging errors i geuss.