Incomprehensible compiler errors

[Stuart]

I'm trying to write an actual program in D, but no matter what I 
do I get stupid errors that mean nothing to me. (Reminds me of 
C++)

   Error 42: Symbol Undefined
   _D8infinity8standard7runtime4IApp4IApp11__InterfaceZ 
Huh? This usually happens if I omit the module statement at the 
top of EVERY DAMN FILE (why???) but in this case I haven't 
omitted it, yet I'm still getting the error.

Also, I get the following error:

   Error 42: Symbol Undefined
   _D3dfl8internal6winapi12__ModuleInfoZ

The code producing this second error is:

        int Run() {
                import core.sys.windows.windows;
                import dfl.internal.winapi;
                MSG msg;
                while (GetMessageA(&msg, null, 0, 0)) {
                        TranslateMessage(&msg);
                        DispatchMessageA(&msg);
                        if (msg.hwnd && !IsWindow(msg.hwnd)) break;
                }
                return 0;
        }

What the HELL is this "ModuleInfo", why is it necessary, why is 
it always missing when a "module" statement is not present, and 
why is it missing NOW?