Philipp Thomas wrote: >> -fms-extensions >> > > BTW on a side note: If at all possible, get rid of that option (i.e. > change the code that needs it), because it allows IMNSHO very dubious MS > extensions to C++. My goal - once things work is compilation without warnings on all supported platforms, with minimal sabatoging of warnings or errors with compiler options. But the first thing I need to do is isolate the actual problem. I have tried a couple of things, and I am getting nowhere. I have added the -fms-extensions compile option - with no effect. I have eliminated the inherited parent class from the class definition - with no effect. I am dealing with enough complexity that I may have screwed up some of my efforts to try to isolate this. I did manage to eliminate a few undefined vtable messages - but that was by eliminating all references to that class. There must be some what to try to isolate or zero in on this. Other suggestions for techniques to zero in on this problem would be greatly appreciated.