 In the case of an exception in user mode code, the operating system parses the thread's _EXCEPTION_REGISTRATION_RECORD list and calls each exception handler in sequence until a handler signals it has handled the exception (by return value) or the list is exhausted.The last one in the list is always the codice_17 which displays the General protection fault error message.Then the list is traversed once more giving handlers a chance to clean up any resources used.