Fix up Start Emulation causing Project 64 to crash out, g_BaseSystem

Source/Project64/User Interface/Main Menu Class.cpp

@@ -77,6 +77,11 @@ bool CMainMenu::ProcessMessage(WND_HANDLE hWnd, DWORD /*FromAccelerator*/, DWORD
 		break;
 	case ID_FILE_STARTEMULATION:
 		_Gui->SaveWindowLoc();
+		//Before we go and create the new system, ensure the previous one has been closed
+		CN64System::CloseSystem();
+		//Ok now g_BaseSystem should definitely be clean for initialization
+		g_BaseSystem = new CN64System(g_Plugins, false);
+		//Now we have created again, we can start up emulation
 		g_BaseSystem->StartEmulation(true);
 		break;
 	case ID_FILE_ENDEMULATION: