This is because these are called zombie processes stuck in some kind of dead lock and no matter what you do, it will not close. If you try quitting it or fore close it, it will not close. So how to over come this situation.
There is only one way to kill these application, and that is through command line. Here are the steps you have to follow.
1) Open Spotlight, Hit Command + Space
2) Type Terminal in it and hit enter.