menustrip in c# windows from

Question

I have a windows from with menustrip containing 19 items. After loading the form if I try to  close the menu items(Right click on menu bar and close), I am able to close first 17 items but not last 2 items. I have changed the order of the items and tried to close. Even after changing, the last two items cant be closed.  I have checked all properties but didnt find any difference. Can any one help in solving my problem. Thanks in advance.