Well guess I was wrong, all the debug assertions I've seen occur in dbgheap.c, never seen one in dbgdel.cpp. But in any case, it still means Khaled is the only one who can do anything about it. Windows can report the error, but only the application can fix it. Also, considering mIRC doesn't crash too often (at least not for me) and mIRC has no "send debug data to mIRC developers" feature, what is the point of linking against the debug RT? If mIRC doesn't provide a way for users to provide debug information, then all it does is increase the exe size.