Improvements to D3D11 detection and error handling.

Windows/MainWindow.cpp

@@ -23,6 +23,8 @@
 
 #include "Common/CommonWindows.h"
 #include "Common/KeyMap.h"
+#include "Common/OSVersion.h"
+
 #include <Windowsx.h>
 
 #include <map>
@@ -640,6 +642,10 @@ namespace MainWindow
 	LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)	{
 		switch (message) {
 		case WM_CREATE:
+			if (!DoesVersionMatchWindows(6, 0, 0, 0, true)) {
+				// Remove the D3D11 choice on versions below XP
+				RemoveMenu(GetMenu(hWnd), ID_OPTIONS_DIRECT3D11, MF_BYCOMMAND);
+			}
 			break;
 			
 		case WM_GETMINMAXINFO: